platinum metals reviewplatinum-clad base metal stirrers for many years molybdenum has been used as...

E-ISSN 1471–0676

PLATINUM METALS REVIEWA Quarterly Survey of Research on the Platinum Metals and

of Developments in their Application in Industrywww.platinummetalsreview.com

VOL. 49 APRIL 2005 NO. 2

Contents

New Stirrer Technology for the Glass Industry 62By Duncan R. Coupland and Paul Williams

Iridium/Carbon Films Prepared by MOCVD 70By Changyi Hu, Jigao Wan and Jiaoyan Dai

Modern Palladium Catalysis 77A book review by Mark Hooper

Potential Applications of Fission Platinoids in Industry 79By Zdenek Kolarik and Edouard V. Renard

Ruthenium Catalyst for Treatment of Water Containing 91Concentrated Organic Waste

By YuanJin Lei, ShuDong Zhang, JingChuan He, JiangChun Wu and Yun Yang

Patents and Copyright for Scientists 98By Ian Wishart

Abstracts 102

New Patents 106

Final Analysis: Thermocouples Compensating Circuits 108By Roger Wilkinson

Communications should be addressed to: The Editor, Susan V. Ashton, Platinum Metals Review, [email protected] Matthey Public Limited Company, Hatton Garden, London EC1N 8EE

Good quality glass has to be homogeneous. Toachieve this, glass melting furnaces have beendeveloped to give a high degree of mixing andcapability to deliver uniform glass into the fore-hearth. However, the necessity to continuouslycondition (heat, cool, or de-gas, etc.) the glassflowing towards the working end can negate someof this design and can cause thermal and composi-tional inhomogeneities in the flowing glass. Thiscould compromise the quality of the finished prod-uct. To produce homogeneous glass it is thereforenecessary to stir the glass in the forehearth, andthis is widely employed. However, the introductionof stirrers has repercussions; the function of stir-ring is of value, but the physical presence of thestirrer is a drawback.

The choice of material for the stirrer helps todetermine the optimum benefit, as the cost, effec-tiveness and durability need to be balanced. Eachof these aspects depends on the final application ofthe glass and the nature of the molten glass, specif-ically, its viscosity, temperature, corrosivity, qualityand value. Stirrers with their glass contact surfacesmade in platinum or platinum alloys provide thebest solution to this issue, but for many installationsites, such as container glass forehearths, where the

value of the product has traditionally been low, thecost of fabricated platinum stirrers has historicallybeen too high.

The introduction in 1994 of ACTTM platinum-coated ceramics changed this (1, 2). ACTTM

technology provided great improvements in theresistance of ceramics to molten glass at relativelymoderate cost by providing enhanced durabilityand longevity compared with prior used unpro-tected ceramic (3).

For glasses of very high value, specifically opti-cal glasses where quality and clarity are paramount,stirrers fabricated from platinum alloys havealways been used, although they have limited dura-bility in high viscosity glass, especially when theglass is used for large components.

Stirrer cores made from molybdenum havebeen found (at least 15 years ago) to provide thestrength that is required by platinum for parts usedin high value glass making, such as in gobbing andhigh energy stirrers. Separation of the platinumand the molybdenum by an oxide diffusion barrierand evacuation of the resulting space are necessaryto avoid the cores from volatilising at temperaturesabove ~ 400ºC.

Other materials evaluated over the years for

Platinum Metals Rev., 2005, 49, (2), 6269 62

DOI: 10.1595/147106705X45604

New Stirrer Technology for the Glass IndustryLONG-TERM BENEFITS FROM THE ‘DIFFUSION CHOKE’

By Duncan R. Coupland* and Paul WilliamsJohnson Matthey Noble Metals, Orchard Road, Royston, Hertfordshire SG8 5HE, U.K.; *E-mail: [email protected]

The function of stirring in glass making is to create uniform, homogeneous glass. Stirringequipment operates at high temperatures and under high mechanical stresses, so stirringdevices have to be robust and often involve large amounts of platinum or platinum alloys. Thestirrers, stirrer bars, blenders, homogenisers, screw plungers and plunging stirrers currentlyused are generally effective in operation, reliable and with predictable lifetimes. Thus therehas been no incentive to improve the technology, and stirrer designs have changed little in thelast twenty or thirty years. However, the current economic climate in the glass industry demandslower costs, improved operational efficiency, and reduced platinum inventories glass makinguses large quantities of platinum, with stirring devices taking a large part of it. To help reducethese amounts work has been undertaken on stirrer technology. and recent developments haveresulted in lower platinum requirements (in some cases by over 90 per cent) without jeopardisingstirring effectiveness or stirrer longevity. Different types of glass stirrers are examined hereand a new concept in stirrer design, a diffusion choke, is described.

stirrer cores and similar applications in the glassindustry have included platinum alloy coated, highstrength oxide dispersion strengthened (ODS)superalloys, but without significant success.However, the recent development of diffusionchoke technology has overturned these failuresand enabled the use of these superalloys. Thispaper looks at the background to the diffusionchoke development and the improvements thatare now possible.

Recent Stirrer HistoryACTTM Platinum Coated Stirrers

ACTTM platinum coating technology has beenused in molten glass furnaces for more than tenyears (1, 2). Some of the earliest applications werecoated ceramic stirrers for application in the sever-est conditions, such as in opal and borosilicate

glass and colouring forehearths (where colour isadded to glass). The objective was to prevent theceramic from being eroded and to allow continu-ous efficient stirring. The effectiveness of theACTTM technology can be seen by the uncorrodedstirrer on the left in Figure 1; all three stirrers hadexperienced six months of continuous service.ACTTM technology is now being used to re-definethe nature of stirrers and to give more advantagesover conventional fabrications, see, for exampleFigure 2.

In a recent application, co-planar ceramic stir-rers with ACTTM platinum alloy coatings, seeFigure 3, replaced helical stirrers fully fabricatedfrom platinum alloy sheet. The improved perfor-mance they achieved in stirring molten TV panelglass has dramatically assisted in this economicallydifficult area. In one case, ACTTM-coated ceramic

Platinum Metals Rev., 2005, 49, (2) 63

Fig. 1 Three stirrers that were usedtogether at the same time for the sametime (approximately six months) in acolouring forehearth. The glass immersionline can be seen.

The stirrers were identical except the oneon the left has an ACTTM platinum coating.

The stirrers rotate in the glass. They are ~1 m in length and made from an alumino-silicate ceramic

Fig. 2 A conventional fabricated helicalscrew glass stirrer made of 10%Rh-Pt. Thisstirrer typically has a life of about 5 years.Such stirrers are used for all glass makingthat is inherently expensive due to the largeamount of precious metal required. Weldedjoins on this stirrer are visible

In a forehearth there may be from 2 to 16such stirrers operating in banks of up to 4.They are mechanically operated in optimumstirring patterns, with the other end of thestirrer being fixed to a geared drive

stirrers replaced traditional fabricated platinumones, and thus reduced the platinum that was beingused from a total of 84 kg to only 8 kg. This reduc-tion was partially accomplished by the superiordesign of the stirrer so that fewer were needed(from 10 to 4), and by the reduced thickness of thecoating as compared to the prior fabricated stirrer.The design of an ACTTM coated stirrer is dictatedby the ceramic and the requirements of the appli-cation. Many different configurations have beendefined and utilised.

Platinum-Clad Base Metal StirrersFor many years molybdenum has been used as

the material of choice for structural applicationswithin the glass furnace as it performs well inmolten glass. However, although it is used exten-sively as electrodes in electrically heated furnaces,if free oxygen impinges on its hot surface, it burnsrapidly. This is a major limitation. To be effectivethe molybdenum must be protected if it is to func-tion at any temperature > ~ 400ºC. Therefore inits major application of resistance-heating elec-trodes, it must be water-cooled to ensure that thezone not protected by immersion in molten glass iskept below this critical temperature.

Platinum does not have this limitation and canbe successfully used in such applications withoutwater-cooling. It is assumed that using platinumwould make an electrode too expensive, but this isnot always the case and the introduction of ACTTM

platinum coating technology has allowed electrodedesigns to be generated that have all the advan-tages of platinum without the disadvantages of

molybdenum. Indeed, in some applications wherea solid electrode is required, iridium, which hasunmatched stability in glasses that are especiallyaggressive when molten, and high environmentalresistance, is now being considered as a viablealternative to molybdenum.

In glass stirrer technology it is desirable to makeuse of the strength of molybdenum for applica-tions where the shear strength requirements arevery high and where unexpected failure would beexpensive. Protecting the molybdenum is critical inachieving this. Platinum cladding has convention-ally been utilised in a simple symbiosis: a platinumalloy cladding protects the strength-donatingmolybdenum. As in many symbiotic relationshipsthere is a parasitic component, and the two mate-rials can, under some circumstances, interact andform potentially detrimental intermetallic phases(4). The effect of this can be seen in Figure 4 whichshows the weight losses observed for a series ofmolybdenum samples protected by platinum coat-ings of high thickness. The simple platinum layercan protect the substrate until interdiffusion andinteraction promote failure of the platinum layer.Once this happens rapid oxidation of the molyb-denum occurs with dramatic loss of weight.

The addition of a ceramic barrier layer to keepthe two metals apart was a natural progression. Aceramic barrier can control interdiffusion and oxy-gen removal from the inner space (the volumebetween the cladding and the molybdenum sub-strate) (5). This situation must be maintained forthe duration of the service life of the component.

These stirrer designs have been used to great


Fig. 3 An ACTTM coated co-planar stirrer as used forhomogenising and disturbing laminar flows of glass.

These vanes will be fully immersed in the glass, withthe glass surface being a few centimetres above theupper vane. The vanes operate in simple rotation buteach pair of stirrers will be contra-rotated

success for several decades, and with care can havelives of more than five years. However, when thecladding fails either by mechanical damage, physi-cal change or chemical attack, the introduction ofoxygen onto the molybdenum can cause a dramat-ic and rapid failure. This failure can be anticipatedand avoided, but if it is unexpected the damage tothe forehearth and the resulting down-time can beextreme.

Alternative core materials have been tested, andsuperalloys are most likely to be suited to thisarduous task. These materials were developedspecifically for the gas turbine industry and weredesigned to have excellent strength, and very goodoxidation resistance up to temperatures of ~1100ºC. Oxide dispersion strengthened (ODS)alloys can, of course, be used to provide strengthat temperatures up to 1300ºC. Some of these ODSalloys have considerable resistance to the harshenvironment above molten glass and also whensubmerged in glass, but they tend to erode rela-tively rapidly at the glass line. This causes both

structural weakening and potential glass coloura-tion problems. It would seem feasible to use aplatinum cladding to negate this weakness, butwork done a few years ago (6) showed that the ten-dency of the nickel in the ODS alloy and platinumto interdiffuse was too great for long term success.

Figure 5 shows an example of a stirrer madefrom an ODS alloy of this type. It was ACTTM

platinum coated and then laboratory tested inmolten TV glass for 300 hours at 1150ºC.Approximately the top quarter of this componenthad platinum deposited directly onto the basemetal substrate. Through-diffusion resulted in thedevelopment of surface oxide on top of the plat-inum. The lower three quarters of the sample hada ceramic interlayer which effectively blocked thediffusion, although there was slight colouration ofthe glass still attached to the sample surface. Thisindicates that iron, nickel or chromium migratedfrom the core alloy. Thus, while ACTTM coatingtechnology offers improvement, a further techno-logical advance is required to allow the effective


Fig. 4 Results for test pieces ofplatinum covered molybdenumthat have undergone air oxidationfor 160 hours at 960ºC followedby 724 hours at 1300ºC.

These molybdenum samples canbe seen to lose weight even whencoated with platinum

Fig. 5 A glass stirrer which has an ACTTM

platinum coating on top of an oxide dispersionstrengthened nickel-based superalloy which isvery similar to PM 2000 alloy.

Approximately the first quarter (on the right ofthis component) had platinum depositeddirectly onto the base metal substrate. On theremaining sample the platinum coating wasseparated from the nickel substrate by anoxide interlayer

-4

-3.5

-3

-2.5

-2

-1.5

-1

-0.5

0

0.5

0 50 100 150 50 100 150 200 250 300 350 400 450 500 550 600 650 700

TIME, hR

ELA

TIV

E W

EIG

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SS

use of the ODS materials.Innovative technology has now been developed

and patented (7), and the design and performanceof a stirrer made using it is described below.

The Diffusion ChokeThe process of melting glass and forming it into

high quality shapes requires stirrers that can oper-ate reliably for long periods in the temperaturerange 1000 to 1300ºC. Technical solutions do exist,but all have limitations either in performance orcost. These include the inherent limitations indesign embodied in ACTTM-coated ceramic stir-rers, or the cost and inherent potential forcatastrophic failure of the extremely strong plat-inum-clad molybdenum stirrers. The diffusionchoke was designed as an alternative to the latter.Elimination of the risk of catastrophic failure can

allow for some potential reduction in the usualplatinum cladding thickness, and hence somemodest cost reduction.

The technology was tested by a stirrer with aPM 2000 stirrer shaft and a 20%Rh-Pt sheet metalfabrication or cladding. A mesh or gauze of finelyknitted 10%Rh-Pt alloy, the diffusion choke, wasplaced between the two materials, see Figure 6.Advantages of diffusion choke technology are:• The diffusion choke is designed to separatecladding from the substrate, and thus reduce thediffusion that arises from contact at high tempera-ture causing the problems seen in Figure 5.• The diffusion choke is designed to maintainan airway to the outside and ensure that adequateamounts of oxygen reach the surface of the core.This enables the inherent oxidation properties ofthe ODS alloy to develop and remain throughout


Fig. 6 The typical structure of a knitteddiffusion choke gauze or mesh made from10%Rh-Pt alloy. Here it is wrappedaround the core of a stirrer

Fig. 7 Schematic diagram of atypical helical bladded stirrer.The position of a diffusionchoke in the form of knittedgauze is indicated in blue. Thiswould then cover the stirrercore before being coated withplatinum

prolonged operation at elevated temperatures. • The diffusion choke restricts oxygen flow tothe alloy surface, and ensures that excessive oxidethickness cannot develop. Under certain condi-tions this might otherwise give rise to anaggressive form of rapid oxidation.• An interesting further advantage results fromthe platinum of the diffusion choke being in con-tact with the core alloy, which has a known effectof increasing oxide stability (8).

A typical stirrer design is shown in Figure 7.This was tested in glass for TVs. The initial test

period was extended from 6 to 20 months, andthough still performing well, the stirrer wasremoved for investigation. Initial visual examina-tion indicated no surface degradation at any pointalong its length. Figure 8 shows sections of thestirrer prior to further dismantling. The dis-colouration at the upper end of the shaft inSection A was crusty and mineralised, indicative ofdeposition from the furnace vapours. At the glassline the platinum alloy was slightly brighter possi-bly indicating some minor surface interaction. Amicrofocus XRF unit examined the composition


Section A

Section B

Section C

Section D

1

2

3

4

5

6

7

8

9

10 11

12

13

Fig. 8 Preliminary sectioning ofa stirrer core of PM 2000 with a20%Rh-Pt sheet metal claddingbetween which was a gauze offinely knitted 10%Rh-Pt alloy.This stirrer was used in a hostileenvironment for 20 months.

The numbers represent positionswhere analyses were performed.

The stirrer has been divided intofour sections:

Section A is the top section linkedup to the drive motor;Section B fits into Section A;Section C fits into Section B andto Section D;Section D is the stirrer blade end

Table I

Microfocus X-Ray Fluorescence Analysis of the Stirrer Surface

Sample Pt, % Rh, % Fe, % Cr, % K, % Ca, % Sb, % As, % Bi, % Ba, %

1 27.4 19.7 0.7 44.1 7.5 0.62 14.5 27.7 0.2 5.2 21.3 31.0 0.13 77.2 17.6 1.1 3.4 0.74 77.9 18.8 2.5 0.75 79.7 19.3 1.06 80.2 19.2 0.67 80.4 19.68 80.1 19.5 0.39 80.1 19.910 80.3 19.711 80.4 19.612 80.9 19.113 80.7 19.3

of the external surfaces, see Table I.Analysis of the upper region of the stirrer, posi-

tions 1 to 6 showed that the yellowish encrustation

was derived from the molten glass probably viacondensation from the gas phase. This is, ofcourse, normal and expected. The rhodium con-tents of the alloy are exactly as the original alloyspecification, within the error expected for theanalytical equipment. On the lower portion of thestirrer there were no foreign elements detected onthe alloy surface except for a trace of barium, aglass component, in the region of the glass line.This lack of any surface impurities after immersionin molten glass indicates that the component hadbeen quite well cleaned before being returned forinvestigation, and thus the lack of evidence ofthrough-diffusion from the substrate was stillunproven. Further disassembly of the stirrer wastherefore needed.

The cladding on Section A slid easily from thebase metal shaft. The diffusion choke was

retained within the 20%Rh-Pt tube, butfurther examination showed this was byvery slight adhesion and minimal ten-sion was required to remove the gauze.The same situation was found for thewhole length of shaft (except, ofcourse, where the fixing screws hadbeen securely positioned to transfertorque on the shaft to the cladding andhence to the stirrer blades themselves).Along most of the length of the shaftthe gauze remained shiny and metallic,but in one region there was some grey-ness and at the very top some gauzewas yellow/brown.

Analyses of the inside of the tubeand of gauze samples at points corre-sponding to the external analyses aregiven in Tables II and III, respectively.

Analysis of the inner surfaces of the20%Rh-Pt protective tubing showedthat no elements were present thatwould not have been present in theoriginal alloy, with the possible excep-tion of one sample below the glass line.Interestingly, the rhodium level in theinside surface of the tube showed anapproximate 3% reduction from theoriginal bulk alloy composition, as did


Table II

XRF Results for the Inner Rh-Pt Tube Surface

Sample Pt, % Rh, % Fe, % Cr, %

1i 79.8 20.22i 79.1 20.93i 83.7 16.34i 83.4 16.65i 83.4 16.66i 82.5 17.58i 82.7 17.39i 82.6 17.410i 82.4 17.611i 82.9 16.9 0.2

Table IV

Microfocus XRF Analysis of the Substrate Core Surface

Sample Pt, % Rh, % Fe, % Cr, % Y, % Ti, %

14 1.0 0.1 79.1 17.8 0.8 1.115 5.8 0.5 73.6 18.2 0.8 1.116a (light) 6.1 0.5 72.9 18.5 0.7 1.216b (dark) 2.5 0.3 75.1 18.5 0.7 2.917 22.6 1.7 56.3 17.7 0.7 1.018 7.4 0.7 72.7 17.1 1.1 0.9

Table IIIa

Analysis of the Outer Surface of the Diffusion Choke Gauze


1g 88.3 11.76g 87.8 12.28g 86.1 13.911g 85.8 14.1 0.1

Table IIIb

Analysis of the Inside Surface of the Diffusion Choke Gauze


1gi 89.6 10.46gi 87.7 11.2 0.3 0.1 0.78gi 85.7 13.7 0.2 0.411gi 85.9 13.0 0.2 0.5 0.3

the average outer surface composition. Analysis ofthe diffusion choke showed where the rhodiumhad gone. This showed a corresponding increasein rhodium content indicating that either a diffu-sion process or a vapour phase transfer processhad been operating. In addition to an increasedaverage rhodium content the diffusion chokegave measurable levels of iron, chromium and tita-nium on the side in contact with the base metalsubstrate, but almost none on the side in contactwith the Rh-Pt tube. The surface of the choke incontact with the core was slightly discoloured, andappeared to have physical contamination ratherthan a chemically-bonded contamination.

PM 2000, the core of the stirrer, is an iron-based ODS alloy with major additions ofchromium and aluminium plus various otherminor ones. The key to its high strength at elevat-ed temperature is the presence of yttria which, as adispersed stable oxide, provides grain boundarystrengthening. Table IV shows the results formicrofocus XRF of the surface of the core PM2000 alloy after service. The absence of values foraluminium is linked to the analytical technique,rather than being a mechanistic issue. Alternateanalytical techniques can be used to confirm thataluminium has been retained.

The presence of the occasional high values forplatinum on the surface of the base metal core wasdue to very small adhered flecks of platinum. Thenature of this tiny platinum-rich particulate has notbeen determined, so it is impossible to say whetherthey have been transported by a vapour phasemechanism or are simple physical artifacts. Visualobservation, however, clearly indicated that a thin,protective surface oxide had been formed. Thiswould be expected to change only slowly allowingprotection to the substrate for a very long time.

ConclusionsThe diffusion choke maintained an effective

barrier to degradation of the stirrer for 20 monthsservice. Indeed, the analyses suggests that thecomponent would have maintained integrity for amuch longer time perhaps comparable to the max-imum life of clad molybdenum of 5 to 10 years.

The in-service trial and subsequent destructive

analysis of the 20%Rh-Pt clad, ODS iron-basedalloy stirrer reported here demonstrates that thereis new technology to overcome many of the prob-lems associated with traditional clad-molybdenumstirrers. The technology offers a breakthrough instirrer design and thus additional help to the glass-maker when using stirrers for improving glassquality. In this trial the stirrer design was simple,with reliance on traditional fabrication skills in itsconstruction. Diffusion choke technology haspotential for use in a wider range of stirrer types,and perhaps additional applications, where highstrength, durability and longevity, without risk ofcatastrophic failure, are paramount.

References1 D. R. Coupland, Platinum Metals Rev., 1993, 37, (2),

622 D. R. Coupland, R. B. McGrath, J. M. Evens and J.

P. Hartley, Platinum Metals Rev., 1995, 39, (3), 983 D. R. Coupland, J. M. Evens and M. L. Doyle, Glass

Technol., 1996, 37, (4), 1084 G. L. Selman, Platinum Metals Rev., 1967, 11, (4), 1325 A. S. Darling and G. L. Selman, Platinum Metals Rev.,

1968, 12, (3), 926 Johnson Matthey Noble Metals, internal communi-

cation, 19917 Johnson Matthey PLC, World Appl. 03/059,826;

20038 C. W. Corti, D. R. Coupland and G. L. Selman,

Platinum Metals Rev., 1980, 24, (1), 2

The Authors

Duncan Coupland manages theTechnology Team of Johnson MattheyNoble Metals in Royston. He isresponsible for all technology aspectswithin the business unit. He was theoriginator of ACTTM technology, nowextensively used in the glass industry.He is interested in all aspects of themetallurgical use of the platinum groupmetals and their utilisation in industrialand scientific applications.

Dr Paul Williams has worked forJohnson Matthey Noble Metals sinceJanuary 1997, as a developmentscientist then as a product specialist forACT™ platinum coatings and fabricatedproducts for the glass industry. He isnow Johnson Matthey’s EuropeanProduct Manager for medical products.He is interested in Nitinol shape memory

alloys and platinum alloys for medical applications, includingimplantable medical devices.


Noble metals are widely used as electrodes ingas sensors because of their unique physical andchemical properties, such as their inertness, goodoxidation resistance, electrical conductivity andcatalytic performance. However, due to sluggishcharge transfer reactions at the sensing electrodeinterface at low temperature (less than 500ºC) (1),a gas sensor constructed with traditional Pt elec-trodes and ZrO2 electrolyte needs to be heated to ahigher temperature to obtain sufficient voltage out-put and a shorter response time. In order toimprove the properties of these sensors, Ir clusterfilms have been prepared by MOCVD (metal-organic chemical vapour deposition) andinvestigated (28). This paper reports on the com-position, structure and electrochemical propertiesof some Ir/C films.

Experimental ProcedureA schematic diagram of a horizontal hot-wall

MOCVD apparatus is shown in Figure 1. The pre-cursor for the Ir/C films was 500 mg of iridiumtris-acetylacetonate, (CH3COCHCOCH3)3Ir,Ir(acac)3. Oxygen and argon were used as the reac-tant and transmission gases, respectively. Thesubstrates were quartz (10 mm × 10 mm × 1 mmthick) and YSZ (yttria stabilised zirconia): 6 mol %Y2O3, (10 mm Φ × 2 mm thick). The temperatureof the precursor (Tsor) was kept at 190ºC. The totalgas pressure in the chamber was fixed at 500 Pa,with argon flow maintained at 50 ml min1. Theprecursor was placed in a small quartz boat in theMOCVD apparatus. The deposition temperature(Tdep) was varied from 450 to 650ºC, for a deposi-tion time of 60 minutes. The flow of oxygen (FO2)


DOI: 10.1595/147106705X45631

Iridium/Carbon Films Prepared by MOCVDOBSERVATIONS AND ELECTROCHEMICAL PROPERTIES RELATING TO OXYGEN ADDITIONS

By Changyi Hu* and Jigao WanKunming Institute of Precious Metals, Kunming, Yunnan 650221, China; *E-mail: [email protected]

and Jiaoyan DaiInstitute of Materials and Engineering, Central South University, Changsha, Hunan 410083, China

Iridium/carbon (Ir/C) films were prepared by MOCVD using iridium acetylacetonate as theprecursor and some electrochemical properties were studied, in particular the effects of oxygenon the carbon content of the Ir/C films. Small additions of oxygen (4 ml min1) to the sourcegas drastically decrease the carbon content of the films. Ir grains are formed, up to ~ 3 nmin diameter, in the amorphous carbon. It was found that Ir/C films with higher carbon contenthave better catalytic performance for measuring the oxygen concentration than Ir/C filmswith lower carbon content. The Ir/C films were used as electrodes in an oxygen concentrationcell, and the sensitivity of the cell to oxygen was recorded. The Nernstian electromotiveforce of the cell is almost the same as that of a similar type of commercial oxygen concentrationsensor from Bosch, but the response time is faster.

Furnace FurnaceManometer

Vacuum pump

PrecursorArgon

OxygenSubstrate

Fig. 1 Schematic diagram of chemical vapour deposition equipment used for the preparation of Ir/C films

was varied from 0 to 10 ml min1.The composition of the deposits was analysed

by X-ray photoelectron spectroscopy (XPS). Theexciting source of the XPS is Al (Kα), the sensi-tivity factors are 4.4, 0.25 and 0.66 for Ir, C and O,respectively. The film structures were also investi-gated by XRD and SEM.

Figure 2 shows a schematic diagram of themeasurement of the Nernstian electromotive force(e.m.f.) of the oxygen concentration cell having anIr/C electrode attached to both sides of a YSZsolid electrolyte. Values of the e.m.f. were mea-sured by changing the partial pressure of theoxygen at temperatures from 300 to 600ºC.

A dynamic test apparatus (9) was used to assessthe performance of the oxygen sensor. The air and

fuel (natural gas) were adjusted to obtain thedesired λ values (normalised air/fuel ratios). Theexhaust gas was usually maintained in a rich con-dition, at λ = 0.95. A solenoid valve allowedadditional air to the burner to switch the exhaustcomposition quickly to lean, when λ = 1.05, thencutting off the additional air and switching back torich.

The sensor voltage output was measured by avoltmeter having an input impedance of 107 Ω.The voltage switching response was determinedusing an oscilloscope, also with an input imped-ance of 107 Ω connected in parallel to thevoltmeter. The response time was defined as thetime taken for the output voltage, recorded on theoscilloscope, to sweep between 600 and 200 mV.


Fig. 2 Schematic diagramof apparatus to measuree.m.f. values of an oxygenconcentration cell. The cellhas YSZ solid electrolyteand an Ir/C electrode

Fig. 3 XPS spectra before argon sputtering (lower curves) and after argon sputtering (upper curves) for Ir/C filmsprepared: (a) without oxygen addition and (b) with oxygen addition. B.E. is the binding energy

(b)(a)

600 500 400 300 200 100 0

B.E., eV600 500 400 300 200 100 0

B.E., eV

1#

1#k

6#k

6#

Ir4d

O1s C1s

Ir4f

Ir4p3

Ir4fIr4d

O1s

Ir4p3

280000

240000

200000

160000

120000

80000

40000

0

120000

90000

60000

30000

0

INT

EN

SIT

Y, c

ps

Furnace

Volt-ohm-milliammeter

Thermocouple

Oxygenflowmeter

Oxygengas

Argon flowmeter

Argon gas Oxygen gas

Oxygenflowmeter

Sample

C1s

ResultsComposition of Ir/C Films

Figure 3 shows the XPS spectrum before andafter argon sputtering (5 kV, 2 min) for Ir/C filmsprepared on quartz substrates with and withoutoxygen addition. Before argon sputtering, carbonwas observed at the surface of the two samples.After sputtering, no observable signals from car-bon were detected for the Ir/C films prepared withoxygen addition (trace 6#k), but signals of carbonwere observed from films prepared without oxy-gen addition after sputtering (trace 1#k).

The effects of oxygen and temperature on thecontents inside Ir/C films prepared on quartz areshown in Table I. The addition of oxygen (from 0

to 4 ml min1) is seen to decrease the carbon con-tent and thus increase the iridium content. There isan increasing trend of carbon content inside thefilms prepared without oxygen addition withincreasing deposition temperature.

Films obtained with the addition of oxygenwere smooth with silver-coloured surfaces: due tothe oxygen reacting with carbon. The reactionproducts (carbon dioxide or carbon monoxide) areexhausted from the deposition chamber.

Structure of Ir/C FilmsFigure 4 shows the surface appearances and ele-

mental maps of Ir/C films prepared without andwith oxygen addition. Film prepared without oxy-


Fig. 4 Elemental maps of carbon for Ir/C films. Top map: Film prepared at 650ºC without oxygen addition.Bottom map: Film prepared at 600ºC with 4 ml min1 oxygen addition

gen addition is seen to have a higher carbon con-tent than film with 4 ml min1 oxygen addition.The carbon is dispersed in the grain boundaries ofthe iridium.

Figure 5 shows characteristic X-ray patterns ofIr wire and Ir/C film prepared under differentoxygen flows. The height of the peak increaseswith increasing oxygen flow, indicating that thecarbon content of the films is decreasing. The X-ray peaks of Ir/C films are displaced in the samedirection, comparable to the X-ray peak of the Irwire. This indicates that the states of carbondeposited in these films are the same.

The peaks in Figure 5 starting at the highestrepresent: standard Ir wire; Ir/C films prepared

with oxygen additions of 10, 8, 4, 0 ml min1,respectively.

Figure 6 shows characteristic XRD patterns ofthe Ir/C films prepared under different depositionconditions. The Ir/C film with higher carbon con-tent has lower broader XRD peaks. Based oncalculations from the half-width of the X-raypeaks, the Ir grains are ~ 3 nm in size, Fig. 6(a),consistent with direct observations by TEM (6).


Table I

Composition of Ir/C Cluster Films Prepared under Different Deposition Conditions

Tdep 500ºC 550ºC 600ºC 650ºC

Flow O2, ml min–1 0 4 0 4 0 4 0 4

Ir, wt.% 89.5 98.6 82.5 94.9 83.6 97.4 66.9 98.8C, wt.% 9.8 0 17.2 4.7 15.1 2.1 32.2 0.6O, wt.% 0.7 1.4 0.3 0.4 1.3 0.5 0.9 0.6

Fig. 5 Characteristic X-ray patterns of Ir wire and Ir/Cfilms prepared in different oxygen flows.Peaks are: top: Ir wire, followed by Ir/C films preparedwith oxygen additions of 10, 8, 4, 0 ml min1

Fig. 6 Characteristics of the XRD patterns of Ir/C filmsprepared under different deposition conditions:(a) Film prepared at Tdep = 650ºC, FO2 = 0 ml min1

(carbon content 32.2 wt.%)(b) Film prepared at Tdep = 550ºC, FO2 = 9 ml min1

(carbon content 9.9 wt.%)

(a)

(b)

6.0200 6.0400 6.0600WAVELENGTH, Å

10.00 50.00 100.002θ

10.00 50.00 100.002θ

8000

7000

6000

5000

4000

3000

2000

1000

CO

UN

TS

CP

SC

PS

Fig. 9 WDS of the white granules on the surface of theIr/C film after argon sputtering

An SEM surface observation of Ir/C filmdeposited without addition of oxygen is shown inFigure 7. The granules on the surface of the film,

etched by argon sputtering, were identified bywavelength dispersive X-ray spectroscopy (WDS),see Figure 8 and 9. These figures show that theblack and white granules (in Figure 7) representcarbon and iridium, respectively. The carbon existsas an amorphous structure determined from theWDS.

Properties of Ir/C Film ElectrodesThe relationship between e.m.f. values at differ-

ent temperatures and the ratio of the oxygenpartial pressures (P1/P2) in the oxygen concentra-tion cell is shown in Figure 10. The Ir/C filmelectrodes were deposited under various condi-tions. P1 is fixed at 0.1 MPa. The theoretical valuesare calculated from the Nernstian equation (10):

e.m.f. = RT/4F ln P1/P2

where R is the gas constant, F is the Faraday con-stant and T is the absolute temperature.


Fig. 7 SEM of Ir/C film deposited without addition ofoxygen (prepared at Tdep = 550ºC, FO2 = 0 ml min1).The upper arrow indicates a black granule and the lowera white granule formed in the Ir/C films

WAVELENGTH, Å

WAVELENGTH, Å

carbon

iridium

Fig. 8 WDS of the black granules on the surface of theIr/C film after argon sputtering

WAVELENGTH, Å

iridium

WAVELENGTH, Å

carbon100

80

60

40

20

0

100

80

60

40

20

0

100

80

60

40

20

0

10000

5000

0

6.240 6.250 6.260 6.2706.255 6.260 6.265 6.270

43.000 44.000 45.000 46.000 43.000 44.000 45.000 46.000

CO

UN

TS

CO

UN

TS

7µmSEI

The difference between the experimental andthe theoretical values may be caused by electricalleakage (11). The e.m.f. values of Ir/C films pre-pared without oxygen addition were found to behigher than those prepared with 4 ml min1 oxygenaddition. This means the catalytic response, tooxygen, of film with more carbon content (pre-pared without oxygen addition) is higher.

Lastly, the response curves of the commercialsensor (BOSCH LSH6) and the oxygen concen-tration cell constructed with Ir/C film and YSZare shown in Figure 11. The voltage outputs arealmost identical, but the response time of the cellis shorter than that of the sensor.

ConclusionsIr/C films were prepared by MOCVD using

iridium acetylacetonate as the precursor. Smalladditions of oxygen to the source gas greatly

decrease the carbon content of the films. Ir grainsare formed up to ~ 3 nm in diameter by the amor-phous carbon. Ir/C films with higher carboncontent have better catalytic performance thanIr/C film of lower carbon content. The electro-chemical properties of the oxygen concentrationcell using Ir/C films as the electrodes is almost thesame as that for a commercial sensor, but theresponse time is shorter.

A research programme is currently beingundertaken to use the Ir/C films as electrodes forcommercial sensors.

AcknowledgementsThis project was supported by National Natural Science

Foundation of China, Grant No. 50171031, and YunnanScientific Project (Program No. 2003 PY10). The authors wouldlike to thank Mr Y. Wang and Senior J. M. Yang for their helpwith sample preparation and SEM observation, respectively.

References1 T. Goto, R. Vargas and T. Hirai, Mater. Sci. Eng.,

1996, A217218, 2232 T. Goto, R. Vargas and T. Hirai, J. Phys. IV, 1993, 3,

2973 R. Vargas, T. Goto, W. Zhang and T. Hirai, Appl.

Phys. Lett., 1994, 65, (9), 10944 B. S. Kwak, P. N. First, A. Erbil, B. J. Wilkens, J. D.

Budai, M. F. Chisholm and L. A. Boatner, J. Appl.Phys., 1992, 72, (8), 3735

5 Y. M. Sun, J. P. Endle, K. Smith, S. Whaly, R.Mahaffy, J. G. Ekerdt, J. M. White and R. L. Hance,Thin Solid Films, 1999, 346, 100


Fig. 10 Relationship between e.m.f. values and the oxygen partial pressure ratio of the oxygen concentration cell

Fig. 11 Voltage-time response curves operating at 300ºC

5

10

15

20

25

30

1 2

¡ ø

¡ ñ

¡ ö

5

10

15

20

25

30

35

1 2

¡ ñ

¡ ø

¡ ö

e.

m.f.

, mV

ln P1/P2

Measuringtemperature 500ºC 600ºC

theoretical value

0 ml min 1 550ºC 650ºC

4 ml min 1 550ºC 650ºC

(a) (b) Graph (a) (b)

TIME, ms

e.m

.f., m

V

BoschCVD Ir/C

1000 2000 3000 4000 5000

1000800600400200

0

!

!"

6 T. Goto, T. Hirai and T. Ono, Trans. Mater. Res. Soc.Jpn., 2000, 25, (1), 225

7 T. Goto, T. Ono and T. Hirai, Inorg. Mater., 1997, 33,(10), 1021

8 T. Goto, R. Vargas and T. Hirai, Mater. Trans., JIM,1999, 40, (3), 209

9 C. T. Young and J. D. Bode, Characteristics of ZrO2-type oxygen sensors for automotive applications,SAE Tech. Paper 790143, Int. Automotive Eng.

Congr. and Exposition, Detroit, Michigan, Feb., 197910 E. C. Sabbarao and H. S. Maiti, in Science and

Technology of Zirconia III, Advances in Ceramics,Vol. 24B, eds. S. Somiya, N. Yamamoto and H.Yanagida, American. Ceramic Society, Westerville,OH, 1989, pp. 731747

11 R. N. Blumenthal and M. A. Seitz, in ElectricalConductivity in Ceramics and Glass, Part A, ed. N.M. Tallan, Marcel Dekker, N.Y., 1974, pp. 35178


The Authors

Professor Changyi Hu is Professor ofMaterials Science at the Research andDevelopment Center, KunmingInstitute of Precious Metals, China. Hismajor work is the preparations of filmsand coatings of precious metals andwork pieces of refractory metals byMOCVD and CVD.

Jigao Wan is a Senior Researcher in theFunctional Materials Division, KunmingInstitute of Precious Metals, China. Hiscurrent research is on oxygen gas sensorsand other sensors.

Dr Jiaoyan Dai is an engineer at theInstitute of Materials and Engineering,Central South University, China. Herinterests include CVD of precious metalfilms, catalysis of precious metals andelectronic materials.


This book is intended as an update to the orig-inal title Palladium Reagents and Catalysts Innovations in Organic Synthesis written by thesame author and published by Wiley in 1995 (1). Itis to be used in conjunction with the originalreview to cover the whole of organopalladiumchemistry, from the past to the present (mid-2003). The book gives a detailed overview of themain recent advances in organopalladium chem-istry from a synthetic organic chemists view point.

The book is organised by types of organic reac-tions that are catalysed or effected byorganopalladium reagents. The first chapter com-prises a very concise and useful summary of thebasic chemistry of organopalladium catalysis. Thisis followed by separate chapters on each type ofsynthetic reaction.

The first types of reaction to be considered areoxidative reactions with Pd(II) compounds. As theauthor states in his introduction, oxidative nor-mally refers to a reaction of Pd where the oxidationstate of the metal is increased. This chapter, how-ever, refers to oxidation in the classical organicsense, for example, the conversion of an alkene toan aldehyde catalysed by a Pd(II) compound. Thenarrative begins with the first major example ofthis reaction, the Wacker process, and proceeds tomore specific and recent examples. This chapter isdetailed and includes some important chemistrycontributed by the author himself. This is obvious-ly an area close to his heart!

Pd(0)-Catalysed Reactions of Halides and Pseudohalides

The third chapter considers Pd(0)-catalysedreactions of sp2 organic halides and pseudohalides.This is the main body of the book, comprisingroughly half of the content (325 pages). It is a good

reflection of both the weight of academic researchinto this area of chemistry, and the increasing levelof industrial interest and application.

This field is often referred to as cross-couplingreactions. The introduction to the chapter tries tomake some sense of the many variations in thistype of reaction, and each subsection describes adifferent type of coupling reaction. The chapter isorganised in a systematic chemical manner basedon the type of substrate reacted with the arylhalide. A useful addition, however, is the inclusionof the generic names for each type of reaction inthe titles and contents. This makes it easy for a syn-thetic chemist to find details on each namedreaction, for example, Heck, Sonogashira, Suzuki,Stille, Negishi and Hiyama, which is often the waycoupling reactions are referred to in practice. Oneimportant area that is included, but not named assuch in this chapter, is the area often referred to asHartwig-Buchwald amination. This reaction is list-ed as arylation of nitrogen nucleophiles andincluded in the general group of C, N, O, S and Pnucleophiles.

This chapter reviews each type of couplingreaction well, with some mention of the historicaldevelopment of the methodology and good detailsof the most recent, important contributions andmethodologies. While it does not aim to providedetails on the synthetic methods, the subject cov-erage is very thorough and the references provideample leads for practical application of the chem-istry. I believe I am reasonably well informed insome areas of coupling chemistry, and I waspleased to see all of the major recent contributionsin the specific areas in the text. Based on thisobservation, it is clear that the author has provid-ed a well-researched and comprehensive overviewof this vast chosen field of palladium chemistry.

Modern Palladium CatalysisPALLADIUM REAGENTS AND CATALYSTS: NEW PERSPECTIVES FOR THE 21ST CENTURYBY J. TSUJI, John Wiley & Sons, Ltd., Chichester, 2004, 670 pagesISBN (hardcover) 0-470-85032-9, £175.00, €262.50; ISBN (paperback) 0-470-85033-7, £60.00, €90.00

Reviewed by Mark HooperJohnson Matthey Catalysts, Orchard Road, Royston, Hertfordshire SG8 5HE, U.K.; E-mail: [email protected]

DOI: 10.1595/147106705X46487

78

Pd(0)-Catalysed Reactions of Allylic Compounds

The next major area reviewed is that of thereactions of allylic compounds. This is a well-established area of chemistry and has both achiraland chiral synthetic utility. There is a useful gener-al introduction to the various types of this reaction.This chapter covers chemistry from 1965 to thepresent, so there is a much to cover. It is wellordered in a logical, chemistry/reagent based sys-tem. Almost every reaction possible with an allylicsubstrate catalysed by Pd is mentioned, and thereferences provide a useful follow-up.

Other Pd-Catalysed ReactionsThe next three chapters cover reactions of 1,2-

and 1,3-dienes and methylenecyclopropanes;propargyl compounds; and alkynes and benzynes.These short chapters (of 20 to 30 pages) provide agood flavour of these less common areas of Pdchemistry and again most of the main issues andrecent advances are covered.

The final three chapters deal with alkenes, andmiscellaneous reactions, and mention palladium-catalysed reactions that the author sees as impor-tant but which do not fit in with the systematicsubject order of the main chapters. This is usefuland interesting to see glimpses of possible future

areas of important chemistry. There is also a usefulset of tables detailing a long list of the ligands men-tioned in the book. On perusal it appears that all ofthe major advances in ligand technology are there.

In conclusion, this monograph is well writtenand a very well researched review of recent years inpalladium chemistry. It provides the reader with areliable starting point for learning about and evenperforming palladium-catalysed reactions. It is def-initely worth the investment.

The author has succeeded in completing his aimto cover the whole of organopalladium chemistry,in a systematic and logical manner. The book canact as a valuable learning tool and reference pointto release the potential of the wealth of palladiumchemistry that is now available.

The only criticism, from my point of view,could be that the book does not try to comparevarious contributions to the fields of chemistry interms of their actual usefulness to the practical orindustrial chemist. However, the author is to becongratulated on taking on such a massive task andin his success in making some sense of the vastexplosion in palladium-catalysed chemistry overrecent years.

Reference1 M. V. Twigg, Platinum Metals Rev., 1996, 40, (3), 126

The Reviewer

Mark Hooper is a Senior Development Chemist in the Catalyst Development Department, at Johnson Mattheyin Royston, U.K. He holds a B.A. (Hons), chemistry, and a D.Phil., in organometallic chemistry from OxfordUniversity. From 2000–2002 he held a post-doctoral position with Professor John Hartwig at Yale University,working on palladium catalysed amination. He joined Johnson Matthey in 2002. He is interested in novelhomogeneous catalysts, especially Pd catalysts for coupling chemistry and anchored homogeneous catalystsand has worked with Smopex for the recovery/ separation of precious metals.

Platinum Metals Rev., 2005, 49, (2)


The potential utilisation of fission-producedplatinum metals (fission platinoids, FPs) as valu-able products has attracted attention in the last fewdecades, as large amounts of spent nuclear fuelhave accumulated worldwide. One metric ton ofspent fuel, at a burn up of 33 GWd/t (gigawattdays per metric ton) contains > 1 kg palladium(Pd), > 400 g rhodium (Rh) and > 2 kg ruthenium(Ru) (1). Indeed, by 2030 spent nuclear fuel couldsupply up to 1000 t Pd and 340 t Rh. This wouldbe a considerable addition to the yield from natur-al sources.

FPs can be isolated from radioactive wastes thatoriginate in the reprocessing of spent fuel by thePurex process. The FPs are contained mainly inthe solid residue left after the dissolution of thefuel at an early processing stage, and in the aque-ous waste stream emerging from the first processcycle (high-level liquid waste). Processes for therecovery of FPs from both fractions have beendeveloped worldwide (2).

The purification of FPs during recovery can beso effective that the radioactivity of the fissionproducts left is compatible with safety regulations.However, there remains the intrinsic radioactivity

of the isolated FPs. Fission Pd contains 17 wt.% ofthe radioactive isotope 107Pd (half-life t½ = 7 × 106

years). Besides, fission Pd only contains stable iso-topes with atomic masses 104 (17 wt.%), 105 (29wt.%), 106 (21 wt.%), 108 (12 wt.%) and 110 (4wt.%). 107Pd is a soft beta emitter (maximum ener-gy, Emax = 0.035 MeV), but the radiation intensityat the surface of a foil of fission Pd metal (0.2 mgcm2) is 520 Bq cm2 (3) and this is higher than per-mitted by safety regulations in most countries. Thespecific beta radioactivity was compiled as 1.7 ×106 Bq g1 (1), while 2.6 × 106 Bq g1 was foundexperimentally (3).

The intrinsic radioactivity of fission Rh and Rumay be a more serious problem. Fission Rh con-sists almost exclusively of the stable isotope 103Rhand trace mass fractions of the isotopes 102Rh (t½ =2.9 years) and 102mRh (t½ = 207 days). Electron cap-ture is the exclusive decay mode of 102Rh and it isthe main decay mode of 102mRh, which also is abeta and positron emitter and undergoes an inter-nal transition. The gamma radiation of the isotopesis rather energetic (0.47 to 1.1 MeV). Radioactivedecay can reduce the radioactivity to an acceptablelevel after a suitable, indeed long storage time (≥ 30

DOI: 10.1595/147106705X35263

Potential Applications of FissionPlatinoids in IndustryBy Zdenek Kolarikretired from Forschungszentrum Karlsruhe, POB 3640, 76021 Karlsruhe, Germany

Present address: Kolberger Str. 9, 76139 Karlsruhe, Germany; E-mail: [email protected]

and Edouard V. RenardAll-Russian Institute of Inorganic Materials, 123060 Moscow, Russia

Amounts of fission-generated platinoids, as recovered from high-level liquid radioactive wastes,could considerably supplement amounts of metals claimed from natural sources. Of particularinterest are fission palladium and rhodium, which can be decontaminated from other fissionproducts to a non-hazardous level. What remains is intrinsic radioactivity which is weak infission palladium, and which in fission rhodium decays to an acceptable level after 30 years.The intrinsic radioactivity should not play a negative role when fission platinoids are appliedto nuclear technology. Some non-nuclear applications of fission platinoids may be possible,if irradiation and contamination of personnel as well as uncontrolled release of the platinoids,are avoided.

years). The specific radioactivity of isolated Rhafter a 5 year storage is ~ 107 Bq g1 (1).

Fission Ru exhibits higher intrinsic radioactivitythan Rh, caused by the isotopes 103Ru (0.0036wt.%, t½ = 39 days) and 106Ru (3.8 wt.%, t½ = 1.02years). 103Ru emits beta particles with Emax = 0.76MeV and little gamma radiation (0.050.61 MeV),and decays to stable 103Rh. 106Ru is a soft beta emit-ter (Emax = 0.039 MeV), which is in equilibriumwith 106Rh (t½ = 30 seconds), a hard beta emitter(Emax = 3.54 MeV), also releasing some gammaradiation (0.510.62 MeV). The stable isotopes are99Ru (2.4 × 104 wt.%), 100Ru (4.2 wt.%), 101Ru and102Ru (both 34 wt.%), and 104Ru (24 wt.%). Thespecific radioactivity of isolated Ru after 5 year and20 year storage has been compiled as 3 × 1011 and1 × 107 Bq g1, respectively (1).

It is clear that intrinsic radioactivity restricts theapplicability of isolated FPs. It has been suggestedthat the radioactive isotopes should be removedeither by current methods of isotope separation orby special methods. Atomic vapour laser (4) andplasma (5) separation processes are applicable toall three FPs, laser separation to remove 107Pd fromfission Pd (6) and electromagnetic separation toremove radioactive isotopes from fission Ru (7).However, all these operations would inevitablyincrease the price of isolated FPs which might notbe acceptable by the market.

In another approach (8), only stable isotopes ofPd and Rh would be obtained as final products iffission Ru was the exclusively separated platinoid,that is: beta decay of 106Ru via 106Rh would give sta-ble 106Pd, while stable 103Rh would be formed from103Ru. However, this would, of course, essentiallyreduce the yield of FPs; large amounts of Pd andRh would be left unexploited in the radioactivewaste.

Of the three FPs, Pd and Rh are most applica-ble. Fission Ru is too radioactive, due to the high106Ru content, while Ru obtained from naturalsources has a lower commercial value than eitherPd or Rh.

The intrinsic radioactivity of FPs does notrestrict their applications in fields in which it is notin conflict with safety regulations, for example, innuclear engineering. In other fields, two require-

ments must preferably be fulfilled: Irradiation and contamination of personnelmust be avoided and, uncontrolled release of the FPs radioactivitymust be suppressed to well below the legally per-mitted level.

The first requirement is fulfilled without specialprecautions in using fission Pd; the major part ofits soft beta radiation is self-absorbed in Pd itselfor in its solid support. The range of the radiationin air is 0.2 cm, and is < 0.002 cm in tissue whichis considerably shorter than the thickness of thehorny layer of human skin. Fulfilling the secondrequirement differs from application to applica-tion.

One precaution is inevitable both in nuclearand non-nuclear applications. Substances contain-ing FPs would have to be treated as radioactivematerials in common operations, such as fabrica-tion, refabrication, regeneration and disposal. Suchoperations would have to be made in correspond-ingly licensed and equipped facilities and respectsafety regulations. However, the impact of this ontotal productions costs would not necessarily be ofgreat importance.

This review outlines the potential for industrialand small scale applications of FPs. It shows thatin some applications the intrinsic radioactivitywould play no role, or a subordinate role.Elsewhere the use of FPs could be made compati-ble with safety regulations, but would not bealways practicable. Due to the critical attitude ofthe public toward nuclear technology and applica-tions, FPs could not be used in the production ofconsumer goods, even if their role in the produc-tion process was indirect and contamination of thefinal product excluded. On the other hand, the FPsmay well be used in the fabrication of products forindustrial use. Applications that are not acceptableare medical uses such as the production of bacteri-cidal and antitumour pharmaceuticals, surgicalimplants, medical equipment and jewellery.

Nuclear Technology In any applications in this field the intrinsic

radioactivity of FPs would play only a minor role.Possible applications are shown below, excluding

Platinum Metals Rev., 2005, 49, (2), bbmm 80

cold nuclear fusion which, although havingpromised to be a revolutionary source of energy,turned out to be a misinterpretation of experimen-tal results.

Structural and Special MaterialsAreas where platinoid additives improve the

properties of structural materials: In the Canadian deuterium-uranium reactor(CANDU), pressure tubes made from a Zr-Nballoy are in contact with heavy water coolant (580K, 11.1 MPa) on the inner side and with CO2

coolant on the outer side. Elemental deuteriumformed in corrosion reactions diffuses towards theouter side of the tubes and weakens them due tohydrogen embrittlement. To inhibit this, the con-centration of deuterium is suppressed by oxidationbelow the dissociation pressure of Zr hydride. Pdcoating catalyses the oxidation, as shown in modelexperiments with pure Zr and hydrogen (9).Associated problems, such as oxygen corrosion ofZircaloy, catalyst deactivation, neutron absorptionby Pd and radioactive waste production wereshown to be manageable (10). A Pd layer on nickel or cobalt-based alloys andstainless steels catalyses the reaction of hydrogenwith oxygen or hydrogen peroxide in water at >150ºC. This lowers the corrosion potential ofthese materials in pressurised water nuclear reac-tors (11). A platinoid catalyses the recombinationof hydrogen and oxygen in a gas stream and,simultaneously, the decomposition of hydrogenperoxide in a water stream, when the streams arein counter-current contact (12). Embrittlement of Zircaloy cladding of oxidefuel rods by fission product cadmium is preventedby Pd (0.252.0 g kg1). The Pd can be blendedwith the bulk of the fuel, dispersed as coating onthe oxide particles before or after their pressing topellets, or applied as a coating on the inner side ofthe cladding tubes (13). The oxidation resistance of the Zircaloy-4cladding of fuel elements is increased by alloyingits surface with Pd. For example, a Pd layer (2 µm)is electroplated onto the Zircaloy-4 surface andannealed at 950ºC and < 104 Pa (14). 60Co-embedded oxide scales are formed on the

surface of stainless steel in boiling water reactors.The formation is reduced by a thin surface film ofPd, deposited either by vacuum evaporation orelectrolysis (15). Pd can be a component of shape memoryalloys, that is, materials acquiring a prescribedform when heated to transformation temperatureand restored to their initial shape on cooling. Suchalloys may be TiNiPd, sputter-deposited as a thinamorphous film and crystallised at 700750ºC (16)and Ti50Pd50xNix, especially when improved bythermomechanical treatment (17). Shape memoryalloys can be used in passive safety systems, ther-mocouplings for pipes and electric drives,equipment for repair and assembly of units, ther-momechanical drivers, dampers, flow rateregulators, thermodetectors, self-operating emer-gency systems, units and elements in electricaltransmission lines and electric contact devices(18). The Ti-0.2Pd alloy is a prospective material forthe construction of containers for solid high-levelradioactive wastes, which are to be disposed in arock salt depository. The passive layers of thematerial are adequately resistant to gamma radia-tion when it is in contact with salt brine (19).

Removal of Hydrogen Isotopes from Gasesand Liquids

Platinoid catalysed reactions can be of impor-tance in gaseous, liquid and solid phases: Tritium, free or bound in tritiated hydrocar-bons, is removed from the off-gas stream of afission reactor by conversion to tritiated water orits mixture with CO2. Catalysed by Pd, Rh or theirmixture deposited on alumina or silica, the reac-tion proceeds at 90500ºC and atmosphericpressure (20). Tritium is removed from the aqueous effluentsof a nuclear plant and directed into an aqueousconcentrate in combining the electrolysis of tritiat-ed water with the catalysed isotopic exchangereaction:

HT(gas) + H2O(liquid) = H2(gas) + HTO(liquid)

Deposited on a styrene-divinylbenzene copoly-mer, Pd catalyses the exchange less efficiently than


Pt, but it can be used in mixture with Pt (21, 22).The catalyst is prepared by agglomeration, crush-ing the agglomerate, pressing it into a cake andcutting catalyst particles from the cake (22). Hydrogen in the primary cooling circuit of agas-cooled nuclear power reactor is separated fromradioactive impurities if it is passed through a Pdalloy film. The cooling gas must be pressurised andfree from moisture and oxygen (23, 24). To prepare a catalyst for hydrogen/oxygenrecombination in a nuclear power plant, a platinoidis deposited on a porous metal, and heated at400850ºC, when it diffuses into the carrier sur-face where it forms an alloy layer (25).Alternatively, a ceramic granular material can becoated with Pd and used in a passive catalytic mod-ule, which is incorporated in a nuclear reactor forhydrogen mitigation during a core-melt accident(26, 27). Alumina beads carrying 0.5% Pd catalyse theH2/O2 recombination to 99% at 25ºC in compact-ed solid radioactive waste stored in sealedpackages. Hydrogen is formed if the waste ishumid and swells as a result of the corrosion ofaluminium, steel and zinc (28).

Hydrogen Isotope Diffusion, Trapping andCleanup

The utilisation of platinoids in the above oper-ations finds broad application in non-nuclearindustry (see later section on HydrogenProduction). Pure Pd metal, but not Pd alloys,exhibits considerable adsorption and permeationcapacity for hydrogen; the capacity decreases in theorder: Pd > Pd95Co5 > Pd90Co10 > Pd95U5 > Pd3U(300600 K, ≤ 50 bar) (29).

Hydrogen isotopes are separated from othercomponents of the gas output of a fusion reactorby permeation through Pd-Ag (75/25 wt./wt.)membranes at 350450ºC. The isotopic effects areH2/D2 = 1.72 and H2/DT = 2.06. The Pd-Ag alloyis poisoned by tritiated methane, but is regenerat-ed by heating in air (30). Efficient devices havebeen constructed and tested in the U.S.A.(Savannah River Site) (31), Russia (32) and Japan(Japan Atomic Energy Research Institute) (33, 34).The dimension and operating conditions of a per-

meator can be calculated by mathematical model-ling (35).

Other materials used in permeation membranesare Pd alloys containing 1040 wt.% Ag, 525wt.% Au, 1020 wt.% Pt or 510 wt.% Rh. Verypromising materials are Pd-Ag or Pd-Au alloyswith additions of Pt, Rh, Ru or Ir. Pd alloyed with25 wt.% Ag, Au and Ru exhibits excellent hydro-gen permeability and mechanical properties, and isalso resistant to hydrogen embrittlement andswelling and fractures caused by helium bubbleformation (36). Other applicable Pd alloys, devel-oped for non-nuclear industry, contain 1030%Ag, 0.55% Au, ≤ 2% Y, 0.22% Ru, ≤ 1% Pt and0.010.5% Al (37).

The methane poisoning is avoided in a double-function membrane reactor which incorporates aPd-Ag tube packed in a Ni catalyst bed. After thebulk of HT in the inlet gas is oxidised to HTOover a Pt catalyst, He is added, and the gas is con-tacted with the Ni catalyst which converts theHTO and CH2T2 into HT, CO and CO2 at310600ºC. A HT product and a He + CO + CO2

waste stream are obtained (3840). A mathematicalmodel accounts for coupled effects of transport-limited permeation of H isotopes and variouschemical reactions (41).

Tritium can be separated from liquid Li in athermonuclear power plant by transfer through aniobium window into a helium stream at 980ºC.The Nb window is protected from oxygen attackon the He side by an electrolytically deposited Pdlayer (0.001 cm). Diffusion of Pd into Nb is pre-vented by an intermediate layer (250 nm) ofyttrium which does not form solid solutions withNb (42). Diffusion through a double-layer Zr-Pdwindow also separates tritium from liquid Li, andalso from Li alloys (for example, Li17Pb83). Li or itsalloy flows on the Zr side of the window, and apurge stream of argon and oxygen flows on theside of the Pd coating. At 450ºC tritium diffusesrapidly through the window and is recovered asT2O. Problems like reaction at the Pd surface andcorrosion deserve attention (43).

Hydrogen isotopes can be removed from fis-sion and fusion liquid coolants by pumpingagainst a partial-pressure drop. A gas containing H


isotopes as impurities is kept in a vacuum (108 Pa)or a reducing atmosphere on the lower concentra-tion side, and H isotopes are permeated through aPd or Pd-Ag (75/25) diaphragm (44) or a Pd-coat-ed Zr membrane (45) into an oxidisingatmosphere on the higher concentration side.There they are oxidised to water (600700 K,upstream pressure 0.00070.03 Pa). The mecha-nism is discussed in (46).

The behaviour of tritium on a Pd-Ag (75/25)cathodic membrane with and without a Pd blackdeposit, that is, the amount of diffused andtrapped tritium, the retrodiffusion, diffusion coef-ficient, tritium concentrations in the alloy sublayerand the diffusion layer thickness, all depend uponthe applied cathodic potential, temperature, Pd-Agmembrane thickness, presence of Pd blackdeposits and time. Without a Pd black deposit, thedouble layer capacitance is 40 µF cm2 and theapparent diffusion coefficient is 3 × 107 cm2 s1 at~ 20ºC. A Pd black deposit increases the diffusioncoefficient to 3 × 103 cm2 s1 (47).

Separation of Hydrogen IsotopesThis separation is based on isotope exchange

reactions in Pd, such as:H2 + Pd-T → HT + Pd-H

andD2 + Pd-T → DT + Pd-D.

The separation factors are:ln αHT = 284/T + 0.03

andln αDT = 114/T + 0.002,

that is, at 296 K, αHT = 2.69 and αDT = 1.47 (48),while the ranges αHT = 2.684.16 and αDT =1.471.54 are given elsewhere (49). Pelletised Pdblack can be used at 0ºC, and the separation fac-tors depend on the starting H2/D2, H2/T2, andD2/T2 ratios (50) and on the temperature (80 to100ºC) (50, 51) (see also (52)).

Chromatography is currently used to separateH isotopes. The adsorbent can be Pd deposited onalumina (51, 53) and on carbon and other supportsin frontal and displacement chromatography (51),and in twin-bed periodic counter-current flow(54). Alternatively, spongy Pd black is used in dis-placement chromatography (55) and Pd on

kieselguhr has been used in a pilot plant and a pro-duction facility constructed in the U.S.A.(Savannah River Plant) (56, 57). Pd can also be car-ried by a sulfonic acid cation exchanger (58).Problems arising from volume changes of Pdadsorbers are avoided if they are in the form ofmoulded granules containing a binder. Theabsorption rate is determined by surface reactionsat 78ºC but mainly by hydrogen diffusion inpores of the adsorbent at 0ºC. Counter-currentcontact of the gas phase with the adsorber ispreferably achieved by intermittent opening ofindependent column sections for the gas flow (see(48) and references therein).

Adsorbers consisting of Pd or Rh on alumina,kieselguhr or other suitable oxide can be coveredby a lipophilic layer (silicon resin, teflon, etc.),which is permeable to hydrogen gas and watervapour but not to liquid water. Then the isotopeexchange reactions are (59):

HD(gas) + H2O(vapour) = H2(gas) + HDO(vapour)

HDO(vapour) + H22O(liquid) = HDO(liquid) + H2O(vapour)

Other Nuclear ApplicationsDissolution of pulverised UO2 pellets in 8 M

HNO3 at 80ºC (a modified head-end operation inthe Purex process) is accelerated if they contain0.11.0 wt.% Ru, Rh or Pd. The platinoid is addedas RuO2, Rh2O3 or PdO to UO2 powder in the fab-rication of the pellets, which are sintered at 1750ºCin hydrogen (60).

Hydrogen ProductionPlatinoid-containing membranes are utilised in

non-nuclear industry for the separation of hydro-gen from other gases. Negligible amounts of FPsmight be released to gaseous products from com-pact metallic or glassy materials. The stability ofFPs dispersed as coatings on ceramic or oxidematerials would have to be checked in each case.The mechanical properties and the plasticity ofPd-containing membranes can be improved whenthey are repeatedly loaded with hydrogen, andthen unloaded (isobarically or isothermally) (61).

Membranes made from Pd alloys containing1030 % Ag, 0.55% Au, ≤ 2% Y, 0.22% Ru, ≤


1% Pt and 0.010.5% Al (B-X alloys) have beenapplied on industrial scale in the production ofhydrogen from ammonia purge gas (37). Pd alloymembranes containing 68 wt.% In and 0.51.0wt.% Ru can be used for purification of hydrogenat 400900ºC and 510 atm (62).

A Pd-Ag alloy can be spread on a thin film of γ-alumina, which is supported by a porous ceramichollow fibre (63), or the alloy or Pd can be deposit-ed electrochemically on a fine metal fabric (2080µm thread and 520 µm mesh) (64). A Pd/porous-glass membrane (65) and a γ-alumina membraneimpregnated with Pd in its bulk volume (66) sepa-rate hydrogen from nitrogen and carbon monoxide.

CatalysisIn this much used application the platinoids are

mostly contained in closed systems and, if FPs areused, the risk of personnel irradiation and contam-ination can be minimised. Release of the FPs to theproduct of the catalysed reaction can be minimisedby the catalyst preparation, and minimum losses ofthe platinoid components are, in any case, strivedfor to achieve long catalyst lifetimes. Thus, in somesystems the application of FPs could be quiteacceptable. Incidentally, the use of an intrinsicallyradioactive element (technetium) has already beensuggested: it strongly increases the catalytic activityof Pd (67).

However, using FPs in automobile catalystswould not be acceptable. The release to the envi-ronment, even if minimised, would be worthy ofconsideration, due to the broad utilisation of suchcatalysts. Data on Pt concentrations in dust, soiland sediments, biological material and naturalwaters has been published (68).

The following examples give a value to the pos-sible extent of platinoid release from a catalyst, andalso illustrate the extent of handling the weaklyradioactive FPs if they are used as catalyst compo-nents.

The lowest release of platinoids can be expect-ed from compact metal bodies or layers. Forexample, Pd-Ru alloys (8090/520 w/w) are usedas foils covered on one or both sides by a porouscopper layer (69). A Pd/Pt/Rh alloy is shaped to acomposite wire, containing in its body a fibre of a

Rh/Y alloy; this is braided into a net (70). Anotherexample is a package in which nets from two dif-ferent alloys (Pd/Rh/Ru/Pt and Pd/Pt/Au) arealternately layered (71). A film of Pd can be sup-ported by a layer of a siloxane polymer on a porouscopper membrane (72). Catalysts of the typePdZnTe0.2, PdZn, or PdZn2 are prepared by reduc-tion with formaldehyde or by metal displacement(73).

A not-so-low release of platinoids might occurfrom catalysts in which platinoids are deposited onporous pretreated oxides: most frequently γ-Al2O3,less frequently TiO2, ZrO2, SiO2, V2O5 or MoO3.They are used either without mechanical support,or on a ceramic support such as cordierite. Thepretreatment of γ-Al2O3 consists of calcining in airat 200ºC (74) or 550ºC (75, 76), after eventual ballmilling in 0.5 M nitric acid (75), or contacting withan (NH4)2SeO3 solution and drying at 50ºC (76).Zr(IV) hydroxide can be converted to a superacidby treatment with an (NH4)2MoO4 solution, dryingat 110ºC and calcining at 600ºC (77).

The pretreated oxides (mentioned in the previ-ous paragraph) are contacted with an aqueoussolution of H2PdCl4, Pd(NO3)2 or RhCl3 at roomtemperature, dried at 50120ºC and heated in air to400ºC (74, 75, 77) or 540ºC (76). The Pd(II) is thenreduced to metal by hydrogen at atmospheric pres-sure and 200ºC (77) or 400ºC (74), and the Rh(III)is reduced to metal at 0.1 MPa and 500ºC (75).

In a wet sol-gel process, Al2O3 sol, for example,is formed by reacting Al isopropoxide with hexy-lene glycol at 120ºC. A Rh(III) solution hydrolysesthe sol at 85ºC to a gel, which is then aged at 80ºC,dried at reduced pressure and heated to 600ºC inan atmosphere of air or nitrogen (78).

Again calcination is the usual final step of thecatalyst preparation if zeolites of various types andionic forms (79, 80), mordenite (81) and siliconnitride (82) are used as carriers for platinoids. Anon-calcined catalyst with encapsulated dicarbonylrhodium(I) is prepared by introducing Rh(III) intozeolite Y by ion exchange with Na(I) and heatingin a CO atmosphere at 120ºC and 1 MPa (83).

On sulfide carriers, Pd or Rh in a valency state> 0 is bound to S atoms. For example, the reactionof bis(2-ethoxyethylxanthato)palladium(II) or


tris(2-ethoxyethylxanthato)rhodium(III) withmolybdenyl dithiocarbamate at 430ºC and 6.9 kPain a hydrogen atmosphere results in the take up ofPd or Rh into highly dispersed molybdenum sul-fide (84).

Charcoal granules can be loaded with Rh(III)from an aqueous chloride solution, and the Rh(III)is converted to an oxide at 220ºC and reduced to ametal crystallite by humidified hydrogen at 325ºC(85). An iron/graphite carrier is loaded with Pd(II)from a solution of (π-C3H5PdCl)2 or π-C3H5PdP(C6H5)3 in benzene and subsequentlycalcined in air at 750850ºC (86).

An organic carrier, the styrene-divinylbenzenecopolymer HP20, is loaded with Pd from a Pd(II)acetate solution. The Pd(II) is reduced by hydro-gen at 100ºC and the obtained catalyst is soakedwith trichlorobenzene or trimethylbenzene (87).

To prepare a silicon carrier, silica gel is treatedwith dimethylethoxysilane or triethoxy(2-ethyl-3-pyridyl)silane and propylamine, or by(dimethylethoxysilylmethyl)diphenylphosphine. Asilicon polymer is formed on the surface which, ifcontacted with an aqueous solution of PdCl2,incorporates Pd(II) bound to a nitrogen or a phos-phorus donor atoms (88).

A polymeric support can also be based onsilane, silicone or carbon fluoride (89), and aporous material carrying a platinoid can be coatedby a layer of a carbon fluoride polymer which ispermeable only to gases (90).

Electrochemical TechnologyIn this area the release of FPs and risks for per-

sonnel are reduced if the FPs are contained incompact and corrosion-resistant parts of theequipment involved. These FPs can be applied tothe production of dimensionally stable anodes,cathodes for hydrogen evolution, platinised titani-um electrodes as diffusion electrodes,three-dimensional electrodes (91), electrodes forfuel cells, monocrystalline electrodes and micro-electrodes in microsensors for organics.

Examples of electrode manufacturing show theextent of manipulation with FPs, and examples ofthe corrosion rate and the lifetimes give a figurefor the FPs expected to be released.

Anodes for electrolytic reactions, made fromamorphous alloys Rh-B (75/25), Rh-B-P(70/20/10) and Rh-B-Ti (60/20/20) are represen-tative of compact electrodes. Their corrosion ratein chlorine evolution from aqueous chloride solu-tions is as low as 0.040.07 µm/year at 200 mAcm2, 1.2 V vs. SCE and 6080ºC (92). Electrodesmade from amorphous alloys, such asPd76xPtxSi18Cu6, need no activation treatment (93).

Platinoid Layer/Ti Support ElectrodesElectrodes consisting of a compact support

carrying a platinoid-containing layer are more typ-ical. In these cases Ti is often chosen as thesupport material. It is treated as follows: It is electrolytically coated with the FeSn2 alloy,immersed in a nitrate solution of Pd, Fe and Cd,and heated to 600ºC. An active layer 0.04 cm thickis formed, containing 3336% Pd. The lifetime ofsuch an anode, used to electrodeposit Zn from a 1M H2SO4 + 1 M ZnSO4 solution, is 255287 daysat 50 mA cm2, 1.6 V and 35 ºC (94). A pre-etched Ti coupon is repeatedly wettedwith a solution of RuCl3, PdCl2, Ti(C4H9O)4 andHCl in butanol, dried at 120ºC and heated to500ºC. This forms an active layer in which Pdoxide is finely dispersed in a solid solution of Ruand Ti oxides, containing 2255 mol% Ru, 0.222mol% Pd and 4478 mol% Ti. The active layer canbe top-coated with a porous layer of Ta2O5,formed by applying a solution of TaCl5 in pentanoland heating to 525ºC. The lifetime of the electrodeis 140 hours in 1.5 M H2SO4 at 50ºC and the anodecurrent density is 7.5 kA m2. In a hypochloritegenerator the electrode operated 24 days in dilutedbrine at a chloride current efficiency of 8085%(95). Ti is mechanically polished and etched by 0.2 Moxalic acid. Then it is repeatedly wetted with asolution of RuCl3, SnCl2 and HCl, then dried at50ºC and heated to 350ºC (450ºC after the lastcycle). A RuO2/SnO2 layer is formed, the compo-sition of which is controlled by adjusting theconcentration of the components in the appliedsolution. At a Ru content of 30 mass%, its maxi-mum lifetime as an anode in 0.5 M H2SO4 at 500mA cm2 and 30ºC is ~12 h (96).


Fuel Cell Catalyst ElectrodesA catalyst electrode for a fuel cell is fabricated

by forming a monoatomic layer of Pd or Rh ongold crystallites (510 nm in diameter) carried bycarbon particles. The metals are underpotentialdeposited from 110 M NaOH or KOH contain-ing 104105 M Pd or Rh (97).

Another catalytic electrode is prepared bydepositing Pd onto a sputter-etched silicon sur-face. A 13.5 MHz radio frequency voltage can beused in an argon atmosphere (0.018 torr) both forthe sputtering (500 W r.f. power input into theresulting Ar gas discharge, 30 s) and the Pd depo-sition (50 W, 5 s) (98).

Electrical Technology andElectronics

The potential acceptability of FPs in this field issimilar to that in the area of electrochemical tech-nology. Examples of applications are: Superconductivity is exhibited at < 2 K by Cr-Ru alloys containing > 17 at.% Ru (99), and hasbeen predicted to be a property of the compoundLiPdHx (100). Ru, Pd and Rh not only enhance thesuperconducting transition temperature of hightemperature superconductors but, for example,also shorten the synthesis of YBa2Cu3O7δ from 60to 10 hours, at a temperature of 880ºC instead ofat 920950ºC (101). The compound Al2Ru is a semiconductor atlow temperature, exhibiting rather anomalousdirect current conductivities of ~ 10 and 0.21 Ω1

cm1 at 300 and 0.46 K, respectively (102). The Pd-Ag alloy (70/30 w/w) does not reactwith the YBa2Cu3O7δ superconductor at 980 and1100ºC. A foil of the alloy can thus serve as a con-ductive barrier between the superconductor and asubstrate (103). A non-porous, ductile and shinycoating of a Pd-Ag alloy can be deposited elec-trolytically from a solution containing PdCl2(NH3)2

or Pd(NO3)2(NH3)2, AgNO3, ammonium acetateor ammonium phosphate plus boric acid and mer-captosuccinic acid or mercaptopropionic acid plussuccinic acid monoamide (104). A Pd coating with increased microhardness can bedeposited from a solution containing PdCl2(NH3)4,ammonium sulfate and a complex of ZnCl2 with

1,3,6,8-tetraazatricyclo(4,4,1,13,8)dodecane (105),or from a solution containing the salt (RH)2PdCl4(R = tetramethylenediethylenetetramine) andammonium sulfate (106). Polypyridine complexes of Ru(NCS)2 and RuCl2are used as sensitisers in solar energy conversioncells based on TiO2 mesoporous electrodes (107).

Further special applications are molecularsuperconductors based on platinoid complexeswith organic ligands, photoelectrochemical cells,microwave components, thin film resistors, ther-mocouples, multilayer structures and superthinwire for IC-chips, amorphous soft magneticrecording materials, magnetic and photorecordingmaterials, antiferromagnetic corrosion-resistantfilms, and sandwich cermet capacitors.

Production of Corrosion ResistantMaterials

In this field as well, the FPs would be incorpo-rated in a solid phase and control of their releaseshould thus be possible. Uses may include: Up to a few per cent of Pd improves or,depending upon the steel composition and type,causes deterioration to the corrosion resistance ofstainless steels in diluted sulfuric acid (108, 109)and in solutions of hydrochloric acid or ferric chlo-ride (110). Pd can suppress a particular form ofhydrogen embrittlement (flaking) of even lowalloy steels, and it can also improve mechanicalproperties (109). Platinoids enhance the corrosionresistance of alloys by modifying the cathodic reac-tion (cathodically modified alloys) (111). Addition of ≤ 5% Pd enhances the resistance ofchromium stainless steels to high-temperaturewater that contains hydrogen (112), to pressurisedsuperheated steam at 1200ºC (109), to ≥ 90% sul-furic acid at ≤ 220ºC (113) and to air oxidation at500ºC (114) and 900ºC (115). A content of ≤ 0.7wt.% Rh improves the stability of chromium stain-less steel toward sulfuric and nitric acids (116) and≤ 0.3 wt.% Ru enhances the resistance of the fer-ritic Fe-40Cr alloy to diluted sulfuric acid (117).Laser surface alloying enhances the resistance to0.5 M HCl by forming a surface layer of fine cellu-lar dendrites containing 52 wt.% Ru (118). Passivefilms have been characterised in 0.5 M HCl at


00.2 wt.% Pd (119), and in 0.5 M H2SO4 and 0.5M HCl at 0.10.2 wt.% Ru (120). Steel 316 containing 0.5 wt.% Pd is passivatedto 1 N H2SO4 by a single cycle of hot pressing andsintering (121). A cathodic alloying additive of Pd(≤ 0.5%) improves the resistance of Cr and Tialloys in non-oxidising acids or reducing mediaand also, depending on which components arepresent, improves the resistance of multicompo-nent stainless steels in aggressive environments(122). Addition of 0.15% Pd or coating withPdO/TiO2 enhances the resistance of Ti in boilingnon-acidic NaCl and MgCl2 solutions (123). Mo-Cr alloys are resistant to inorganic and organicacids if they contain ≤ 10 wt.% Pd or Ru (124).Promising corrosion resistance in air is exhibitedby alloys Al47Ru53, Al48Ru51Y, Al44.5Ru50.5Cr5 andAl44.3Ru50.2Cr5B0.5 at 1100ºC and by alloysAl46Ru52Sc2 and Al43Ru52Sc5 at 1350ºC (125). Timetal or Ti-based alloys are resistant to acid chlo-ride brines, if they contain 0.1% Ru (126).

Surface alloying of a Pd plated Ti alloy isachieved by bombarding with Xe ions which dis-perse Pd homogeneously in the surface layer. Thissuppresses corrosion in boiling 1 N H2SO4 (127).The mechanism of the beneficial effect of Pd onthe oxidation resistance of Mo-W-Cr alloys to airand oxygen at 10001250ºC is elucidated in (128).

Miscellaneous ApplicationsA metallic and a carbon-containing material can

be joined if a Pd/Si brazing material and an activemetal (Ti, Zr, etc.) or hydride are placed betweenthe surfaces and heated in vacuum (129). Pd canbe a component of high temperature strain gaugealloys, such as Au-Pd-Cr, Au-Pd-Cr-Ni, Au-Pd-Cr-Pt-Al or Au-Pd-Cr-Pt-Fe-Al-Y (130). Otherpotential applications are hydrogen getters in vac-uum cryogenics, cryogenic temperature sensitiveelements and crucible materials for growing crys-tals at superhigh temperatures.

Conclusions[1] Although fission platinoids (FPs) separatedfrom high-level radioactive wastes will have resid-ual radioactivity, this need not be an insuperable

barrier to their industrial use in particular cases.[2] A wide range of applications where the use ofFPs might be possible has been identified. Thisincludes applications in the nuclear industry,where the materials involved are themselvesradioactive or become radioactive during opera-tion, and other applications where the impact ofthe residual radioactivity could be satisfactorilycontrolled.[3] Any industrial utilisation of FPs must meet thefollowing general criteria: The cost of separating, processing and usingthe FPs should not exceed the costs of using nat-urally derived platinum group metals. Irradiation and contamination of personnel aswell as uncontrolled release of the FPs into theenvironment must be avoided. It must be ensured that recycling of platinumgroup metals, which frequently occurs in industry,does not result in the contamination of the gener-al stock of the metals by the weakly radioactiveFPs. Especially, any risk of introducing the FPsinto materials which later can be used in medicineor jewellery must be excluded. It has to be assessedwhether this could be guaranteed by commonsafety regulations for the treatment of radioactivematerials (which in many countries have becomevery strict in recent decades) or whether addition-al safeguards must be introduced by authoritiesand efficiently established by the industry.

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95 Eltech Systems Corp., U.S. Patent 4,517,068; 198596 C. Iwakura and K. Sakamoto, J. Electrochem. Soc.,

1985, 132, (10), 242097 IBM Corp., U.S. Patent 4,457,986; 198498 General Electric Co., U.S. Patent 4,395,322; 1983

99 Y. Nishihara, Y. Yamaguchi, M. Tokumoto, K. Takedaand K. Fukamichi, Phys. Rev. B, 1986, 34, (5), 3446

100 D. Singh, R. E. Cohen and D. A. Papaconstantopoulos,Phys. Rev. B, 1990, 41, (1), 861

101 Yu. M. Shulga, E. N. Izakovich, V. I. Rubtsov andB. F. Shklyaruk, Platinum Metals Rev., 1993, 37, (2),86

102 P. Volkov and S. J. Poon, Europhys. Lett., 1994, 28,(4), 271

103 J. L. Porter, T. K. Vethanayagam, R. L. Snyder andJ. A. T. Taylor, J. Am. Ceram. Soc., 1990, 73, (6), 1760

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106 Moscow Inst. Fine Chem. Technol., Soviet Patent1,724,740; 1992

107 T. Renouard, R.-A. Fallahpour, Md. K. Nazeeruddin,R. Humphry-Baker, S. I. Gorelsky, A. B. P. Leverand M. Grätzel, Inorg. Chem., 2002, 41, (2), 367

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Metall., 1987, 21, (10), 1369111 H. Potgieter, Report M397, Mintek, Randberg,

January 1990, 13 pp., ISBN 0-86999-876-5112 General Electric Co., U.S. Patent 5,147,602; 1992113 Mitsubishi Jukogyo K.K., U.S. Patent 5,151,248;

1992114 S. C. Tjong and J. B. Malherbe, Appl. Surface Sci.,

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(Houston), 1995, 51, (4), 312118 S. C. Tjong, J. S. Ku and N. J. Ho, Surf. Coat. Technol.,

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(3), 98


The AuthorsZdenek Kolarik retired from the Forshungszentrum Karlsruhe in 1998. He was a member of theresearch staff in the Institute of Hot Chemistry, followed by the Institute of Nuclear Waste. Hisparticular interest was separation chemistry, especially solvent extraction. He participated in workaimed to refine reprocessing of spent nuclear fuel by the Purex process and adapting the processto fast breeder fuel. He also participated in developing a process to separate actinides fromradioactive high-level liquid wastes.


Edouard Renard is a group leader at the A. A. Bochvar All-Russian Institute of InorganicMaterials, Moscow. He works in separation chemistry, particularly with solventextraction. His research work has been directed to further the development of the Purexprocess for reprocessing fast breeder fuel and recently to the development of a processfor the recovery of fission platinoids from radioactive high-level liquid wastes.


With advancing industrial development inChina, water pollution is becoming an increasinglyserious problem. The chemical, petroleum, phar-maceutical, pesticide, electroplating and cokeindustries, paper manufacture and sugar refining allproduce large quantities of organic wastewater.Efficient processing of wastewater is important toprevent water sources from becoming polluted.Processing highly concentrated organic wastewateris difficult, even by biochemical methods; directburning is very expensive, and high temperatureoxidation has a low conversion percentage andfails to eliminate ammonia. Other technologieshave looked at destroying organic waste and clean-ing ground water (1, 2).

Wet air oxidation (WAO) is a thermal liquid-phase process in which organic substances areoxidised in wastewater by air at high temperature andpressure for long treatment times (36). Ammonicnitrogen and cyanide, are difficult to remove. WithWAO, the chemical oxygen demand (COD) conver-sion percentage of organic wastewater is 60 to 96%.The conversion of phenol and sulfur-containingorganic compounds is nearly 99 %.

Catalytic Wet Oxidation ProcessThe CWOP is a liquid-phase oxidation process

using a solid catalyst in which organic compoundsin aqueous solution are oxidised by oxygen or air at

elevated temperatures and pressures. Aqueous-phase deep oxidation can be carried out atcomparatively low temperatures and pressures (7).Various catalysts have been tested to reduce theseverity of the reaction conditions and to improvethe rate of the oxidation reactions of WAO (8, 9).Heterogeneous platinum group metal (pgm) cata-lysts are the ones generally selected.

For successful implementation of CWOP tech-nology it is necessary to use efficient and durablecatalysts and to determine the optimal processconditions. Ruthenium was selected as it is strong-ly resistant to corrosion from both acidic and basicsolution at comparatively high temperatures andpressures. Catalyst deactivation can be related tothe dissolution of metal on the catalyst surface dueto pH changes in the reaction solution; however,although the pH of wastewater changes, the per-formance of Ru-based catalysts remains steady.Alumina and titania were examined as catalyst sup-port materials. Titania was favoured because of itschemical stability, and the strong metal-supportinteraction in Ru/TiO2 catalyst. Attention was alsopaid to the active components and manufacturingtechnology (1014).

In CWOP technology, both pgms and non-noble metals are the active catalyst ingredients.Active ingredients are prone to run off the surfaceof non-noble catalysts due to changes in pH in the

DOI: 10.1595/147106705X45640

Ruthenium Catalyst for Treatment of WaterContaining Concentrated Organic WasteBy YuanJin Lei*, ShuDong Zhang, JingChuan He, JiangChun Wu and Yun YangKunming Institute of Precious Metals, Kunming, Yunnan 650221, China; *E-mail: [email protected]

The catalytic wet oxidation process (CWOP) is a promising technique for the treatment ofhighly concentrated organic wastewater that is difficult to degrade biochemically. This techniqueis based on the wet air oxidation (WAO) method of treating industrial effluent in use formany years. WAO is a thermal liquid-phase process whereby organic substances in highlyconcentrated wastewater are oxidised by air at high temperatures and pressures, for longperiods of time. Removal of ammonic nitrogen and cyanide is, however, difficult. The CWOPaims to improve on the disadvantages of the WAO method. Tests were conducted to find thebest catalysts. Catalyst CWO-11 reduced the severity of the reaction required and improvedthe chemical oxygen demand and the total nitrogen conversion of organic wastewater.

reaction solution. However, pgm catalysts have ahigher stability and activity.

Tests were conducted to find the best catalyst.Activity tests were undertaken in a batch reactoroperated at 250ºC, with a stirrer, using air as oxi-dant. Titania-supported catalyst was found to havehigher activity than alumina-supported catalyst.Addition of a Group IIIB (rare earth) element tothe pgm improved catalytic performance (15, 16).The rare earth element acted as an auxiliary cata-lyst.

In the industrial tests the chemical oxygendemand (COD) and total nitrogen (TN) conver-sion percentage of organic wastewater by thecatalysts approached 99%. A catalyst with goodperformance (CWO-11) was selected and com-pared with a commercial catalyst of the same typeusing industrial wastewater. CWO-11 was found tobe efficient at converting organic compounds inindustrial wastewater that are difficult to convertbiochemically to CO2, N2 and H2O, see theScheme. The CWOP equipment occupies lessspace than the biochemical method, and the ener-gy produced during the oxidation can be recycled.

Experimental WorkThe carriers comprised mini-balls of 5 mm

diameter TiO2 or Al2O3, of specific surface area1020 m2 g1, prepared by mechanical means. Thecarriers were soaked with active components ofplatinum group metals and auxiliary components,

such as Ce, La, etc. The catalyst was then dried,calcined and reduced. All catalysts were preparedin this way.

The organic wastewater used to evaluate thecatalyst comprised:• Simulated organic wastewater composed ofammonium sulfate and oxalic acid in amounts 28.3g l1 and 7.4 g l1, respectively, in distilled water.• Organic wastewater produced by a coke ovenplant (in Kunming). The COD and TN (totalnitrogen, including ammonic nitrogen, cyanide,and so on) are 4000 to 5000 mg l1 and 2000 to3000 mg l1, respectively. This wastewater typicallyalso contains hydrocarbons, benzene, phenol andits derivatives, cyanide, ammonic nitrogen, sulfur-containing organic compounds, NH3 and H2Sdissolved in aqueous phase.

Simulated Laboratory EvaluationsThe reaction conditions were kept constant

throughout the tests. Temperature was at 250ºC.The reaction vessel was equipped with a mechani-cal stirrer with a fixed stirring rate of 1000 rpm.

Organic wastewater was poured into the 500 mlflask. Catalyst (16 g) was then added, and air wasintroduced at a pressure of 28 kg cm2. The reac-tion was free from external diffusion limitations.Diffusion is an indispensable procedure in a het-erogeneous catalytic reaction. An improved flowrate for the reaction solution can eliminate theeffect of external diffusion. If the reaction rate


Oxidation reactions typically taking place by catalysis in a CWOP reactor

Hydrocarbon (HC) (phenol, benzene):O2 O2 O2HC ⎯⎯→ aldehyde or alcohol ⎯⎯→ organic acid ⎯⎯→ CO2 + H2O (i)

NH3, ammonic nitrogen, cyanide and N-containing organic compounds:4NH3 + 3O2 ⎯⎯→ 2N2 + 6H2O (ii)

H2S and S-containing organic compounds: H2S + 2O2 ⎯⎯→ H2SO4 (iii)Scheme

COD of wastewater before reaction COD of wastewater after reactionCOD conversion, % = ⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯ ×100%

COD of wastewater before reaction(a)

does not change along with the stirring rate (1000rpm), the reaction is free from external diffusionlimitations.

Catalytic runs of 30 minutes duration were per-formed, after which the reaction was stopped byinterrupting the air supply. The COD percentageconversion of organic wastewater was calculatedaccording to Expression (a). Similarly, the TNcontent before and after the reaction can be usedto give a conversion percentage.

Simulated Industrial Conditions in A Pilot PlantIn this method 1 litre of solid catalyst was used

in each of the three fixed-bed reactors; air andorganic wastewater were continuously pumped in.The water flow used was 4 l h1 (liquid hourlyspace velocity (LHSV) = 1.3 h1) to treat the waste-water. A flow diagram of a simulated industrial testin the pilot plant is shown in Figure 1. The reactoris similar to one used for practical industrial oper-ation. Four experiments were performed.

Results and DiscussionsReproducibility of Conditions

For consistent evaluation and to differentiatebetween catalysts it is important to select suitableequipment and good evaluation conditions. A 500ml batch reactor was selected. Wastewater fromthe coke oven plant (carbonising water containingphenol, benzene, carbon dioxide and hydrocar-bons) was evaluated twice using the same catalyst.

Table I shows that the COD conversion per-centages in the two experiments were very closewhen the same equipment and conditions wereused. This confirms that equipment and catalystevaluation conditions were comparable.

Catalyst Evaluation by Batch ReactorThe CWOP is usually carried out at high tem-

perature and pressure in an oxidative medium, thepH of which can vary greatly. The pH of the reac-tion system in the batch reactor was measuredbefore and after the reaction, at each reactor exitpoint. The pH of the reaction system varies, forexample with the reactions:

Hydrocarbon + O2 → aldehyde + O2 →organic acid + O2 → CO2 + H2O

The catalysts tested for the purification ofwastewater comprised carriers alumina or titania,and active components such as Pd, Ru and GroupIIIB elements. Table II gives conversion data forwastewater from the coke oven plant. The catalyst


Fig. 1 Flow diagram of a simulated industrial test with three reactors where pH is measured at each reactor exit point

Table I

Repeated Runs Using Coke Oven Wastewater

Number Catalyst CODof runs conversion, %

1 CWO-1* 83.852 CWO-1 83.82

* CWO-1 is similar to catalyst CWO-11

Wastewater tank

Air compressor

Pump

Heater

Reactor 1

Reactor 2 Reactor 3

Condenser

Gas-liquid separator

Exhaust

Treated water

system CWO-2 Pd/Al2O3 is seen to be effectivefor COD conversion but not for TN conversion.Changing the active catalyst component to Ru andthe support to TiO2, as in CWO-7 and CWO-12,increased the TN conversion percentage.

More effective catalysis was obtained when aRu-Group IIIB catalyst was used, as in CWO-8,CWO-10 and CWO-11. CWO-11 was the mosteffective. Both the COD percentage conversionand the TN percentage conversion of CWO-11were very high. The catalyst system CWO-9, whichcontained Ru, Pd and a Group IIIB addition/TiO2

showed no advantage over the above catalysts.

Comparison with a Commercial CatalystThe performance of catalyst CWO-11 was

compared in the batch reactor under identical reac-tion conditions with one of the best availablecommercial catalysts. This catalyst generally oper-ates under similar conditions and with similarwastewaters. The results (Table III) show that theCOD and TN percentage conversions of catalystCWO-11 were higher than those of the commer-cial catalyst, with the difference for TN conversionbeing more pronounced.

Preliminary Examination of Changes inCatalyst Breaking Strength

Knowing the breaking strength of a catalyst isimportant as catalysts in fixed-bed reactors need tobear high pressures, especially in the lower part ofa reactor, where catalyst could be crushed, leadingto a drift of active components from the catalystsurface, and reduced catalytic activity. The break-ing strength of the catalyst is defined by thepressure applied by steel plate as the catalyst isbeing broken. Measurements of catalyst strengthwere taken by a hand crusher method, duringwhich a steel plate slowly crushes the catalyst.

The CWO-11 catalyst was tested under similarsimulated conditions of reaction pressures: 90 × 2,75, 60, 50 × 2 kg cm2, and with large temperatureincreases and decreases. The processes were car-ried out one immediately after the other for 6cycles for 58 hours (20 h for the reaction and 38 hfor the temperature changes), see Figure 2.

The breaking strengths of the catalysts beforeand after being used for 58 hours were measured.Ten samples of each kind of catalyst were ran-domly chosen for testing. Table IV shows theresults. The data indicate that catalyst strength


Table II

Evaluation of Different Catalyst Systems Using Wastewater from a Coke Oven Plant

Catalyst Catalyst system COD conversion, % TN conversion, %

CWO-2 Pd/Al2O3 79.8 5.6CWO-12 Ru/TiO2 77.1 53.6CWO-7 Ru/TiO2 78.3 43.8CWO-8 Ru-Group IIIB/TiO2 80.4 44.8CWO-10 Ru-Group IIIB/TiO2 74.9 33.5CWO-11 Ru-Group IIIB/TiO2 85.2 66.5CWO-9 Ru-Pd-Group IIIB/TiO2 76.8 48.7

Table III

Comparison of Catalysts

Catalyst COD conversion, % TN conversion, %

CWO-11 (Kunming Precious Metals Institute) 85.2 66.5

Similar commercial catalyst (Osaka Gas Co. Ltd., Japan) 83.1 51.1

Table IV

Change in Catalyst Breaking Strength Before and After Use

Sample number 1 2 3 4 5 6 7 8 9 10

New catalyststrength, kg 2.8 3.3 3.4 3.5 3.5 3.5 3.5 3.7 3.8 4.0

Average strength, kg 3.5

Catalyst strengthafter 58 h, kg 2.6 3.3 3.3 3.4 3.4 3.5 3.5 3.6 3.6 4.1

Average strength, kg 3.4

shows no obvious changes after testing over 6-cycles, each lasting for 58 hours. The catalyst couldthus be used for long periods without crumbling.

Results of Simulated Industrial Tests in aPilot Plant on Catalyst CWO-11

As Table V shows, the COD percentage con-version for Reactor 3 exit point (R-3) is ~ 99.9%,(from 16,483.6 for raw wastewater down to 16.48)

and the TN percentage conversion has reached100% (3528 for raw wastewater down to 0). TheTN conversion percentage at Reactor 2 exit point(R-2) has also reached 100%.

Table VI shows that the TN percentage con-version at Reactor 1 exit point (R-1) has reached100%. The COD percentage conversion atReactor 2 exit point (R-2) is up to 99.9%.

In Table VII, the TN conversion percentage


0 2 4 6 8 1 00

2

4

6

8

Str

en

gth

(kg

)

N u m b e r

N e w C a ta lys t C a ta lys t u s e d fo r 5 8 h o u rs

Table V

Tests on CWO-11 with Simulated Industrial WastewaterExperimental conditions: air pressure: 70 kg m–2, temperature: 250ºC, water flow*: 4 l h–1

Wastewater sample O2, pH COD, TN, Flow rate, Exhaust% mg l–1 mg l–1 l h–1 volume, l h–1

Raw wastewater 20.8 9.1 16,483.6 3528 - -R-1 exit point** 12.2 3.5 7905.4 3.36 4.0 554.4R-2 exit point 7.9 5.0 414.44 0 3.9 529.4R-3 exit point 7.1 3.8 16.48 0 3.96 523.4

*Wastewater moves smoothly and continuously, and is not recirculated. **Exit points from Reactors 1, 2 and 3 are shown in Figure 1

Fig. 2 Test results of the breakingstrength of new catalyst and thesame catalyst after being usedcontinuously for 58 hours

SAMPLE NUMBER

ST

RE

NG

TH

, kg

can be seen, at R-3 to reach 100%. However, theCOD conversion percentage at R-3 is only up to68%.

Table VIII shows, the COD percentage con-version at R-3 is up to 99.2%, while the TNpercentage conversion reaches 99.9%.

Thus, experimental conditions of 70 kg cm2

and 250ºC and also of 90 kg cm2 and 270ºC canmeet the requirements for use in the conversion ofwastewater using catalyst CWO-11. An air pressureof 70 kg cm2 and reaction temperature of 250ºCwould be economically more desirable.

ConclusionsWe have obtained a new catalyst (CWO-11) for

use in the catalytic wet oxidation process that iseffective for converting organic compounds insimulated wastewater and wastewater from a cokeoven plant into CO2, H2O and N2. CWO-11 has ahigher activity for COD and TN conversions thana similar commercial catalyst. The COD and TNconversion percentages of organic wastewater areup to 99%.

CWO-11 been used in scaled-up reactors, in abatch reactor in the laboratory and in a continuous


Table VI

Tests on CWO-11 with Simulated Industrial WastewaterExperimental Conditions: air pressure: 90 kg m–2, temperature: 270ºC, water flow: 4 l h–1

Wastewater sample O2, pH COD, TN, Flow rate, Exhaust volume% mg l–1 mg l–1 l h–1 l h–1

Raw wastewater 20.8 8.5 16,483.6 3640.0 - -R-1 exit point 9.1 4.2 412.09 0 4.0 566.6R-2 exit point 8.5 4.0 11.77 0 3.86 542.2R-3 exit point 5.8 3.9 11.77 0 3.96 528

Table VII

Tests of CWO-11 with Simulated Industrial WastewaterExperimental conditions: air pressure: 50 kg m–2, temperature: 230ºC, water flow: 4 l h–1

Wastewater O2, pH COD, TN, Flow rate, Exhaustsample % mg l–1 mg l–1 l h–1 volume, l h–1

Raw wastewater 20.8 8.5 16,483.6 3640.0 - -R-1 exit point 15.8 5.4 12,166.5 1372.0 3.96 548R-2 exit point 12.3 3.5 10,890.9 2.160 3.92 518.2R-3 exit point 8.4 3.6 5214.2 0 4.0 482.6

Table VIII

Tests on CWO-11 with Wastewater from a Coke Oven PlantExperimental conditions: air pressure: 70 kg m–2, temperature: 250ºC, water flow: 4 l h–1

Wastewater Reaction O2, pH COD, TN, Flow rate, Exhaust sample time, min % mg l–1 mg l–1 l h–1 volume, l h–1

Raw wastewater 0 20.8 8.9 3000.5 756.0 - -R-3 exit point 45 15.5 5.4 33.21 0 4.4 269.7R-3 exit point 45 15.0 2.5 14.53 1.12 4.04 291.6Average value 45 15.2 4 23.87 0.6 4.2 280.6

process in a pilot plant. This method of catalystevaluation has effectively differentiated betweencatalysts of different performance.

It is planned to increase and improve themechanical strength of the catalyst and to useCWO-11 in further industrial applications.


The Authors

YuanJin Lei is a Professor of Chemistry atKunming Institute of Precious Metals,China. He has has been working in the areaof catalytic materials for forty years. Hismain interests are the development ofcatalytic gas sensors, environmentalcatalysts, petrochemical catalysts, etc.

ShuDong Zhang has a Master of EngineeringDegree from Kunming Institute of PreciousMetals. He has been working in the area of noblemetal catalysts since 2002.

JingChuan He is a senior chemical engineer atKunming Institute of Precious Metals. Hisresearch interests include heterogeneouscatalysis of noble metals and catalytic gassensors.

JiangChun Wu is a senior chemical engineerat Kunming Institute of Precious Metals. Shehas worked in analytical chemistry for the lastten years, and was involved in testing theperformance of the catalytic gas sensor.

Yun Yang is a mechanical engineer atKunming Institute of Precious Metals. She isinterested in catalytic gas sensors.

References1 L. Davidson, Y. Quinn and D. F Steele, Platinum

Metals Rev., 1998, 42, (3), 902 N. Korte, L. Liang, R. Muftikian, C. Grittini and Q.

Fernando, Platinum Metals Rev., 1997, 41, (1), 23 V. S. Mishra, V. V. Mahajani and J. B. Joshi, Ind.

Eng. Chem. Res., 1995, 34, (1), 24 D. Duprez, F. Delanoe, J. Barbier, P. Isnard and G.

Blanchard, Catal. Today, 1996, 29, (14), 3175 Jin Yi Song et al., Environmental Catalytic Materials

and Applications, Chemical Industry Press, Beijing,2002 (in Chinese)

6 N. M. Dobrynkin, M. V. Batygina and A. S. Noskov,Catal. Today, 1998, 45, (14), 257

7 St. G. Christoskova, M. Stoyanova and M.Georgieva, Appl. Catal. A: Gen., 2001, 208, (12), 243

8 F. Luck, Catal. Today, 1996, 27, (12), 1959 J. Levec and A. Pintar, Catal. Today, 1995, 24, (12),

5110 Wang Yong Yin et. al., Progr. Environ. Sci. (China),

1995, 3, (2), 3511 U. S. Patent 4,115,264; 197812 J. Levec, Appl. Catal., 1990, 63, (1), L113 Jiang Yi et al., Environ. Sci. (China), 1990, 11, (5), 3414 Japanese Patent 64-47,451; 198915 Japanese Patent 64-30,695; 198916 S. Imamura, in Catalysis by Ceria and Related

Materials, ed. A. Trovarelli, Imperial College Press,London, 2002

98Platinum Metals Rev., 2005, 49, (2), 98101

Intellectual property is an intangible asset, but itconfers legal property rights similar to those oftangible assets (land, equipment, etc.). Thus,patents and copyright can be bought and sold, orleased (licensed) for money. A working scientistwill frequently come across patents in the back-ground research. In some areas of technologypatents are by far the main type of technical publi-cation, so it is important to understand thesedocuments and their context, and not be undulyinhibited by their forbidding appearance.

This article will give advice to practising scien-tists regarding patenting.

The Purpose of PatentsA patent is a bargain between the State and an

inventor. In return for the inventor describing theinvention to the public for the advancement ofscience and technology the State rewards theinventor with a limited monopoly that will preventunauthorised commercial use of the invention.

The publication of a patent is intended toincrease human knowledge, and the inventor hasto describe to the skilled reader how to make theinvention work. The inventor is granted a monop-oly period, usually of 20 years, during which timethe inventor can exploit the invention for financialreward. In most countries the monopoly will be for20 years, but because of the delays in gettingapproval, for instance in medicine and agrochemi-cals, the time may be extended by up to 5 moreyears. Renewal fees must of course be paid for thepatent to remain in force.

In almost all countries, priority in patenting isgranted to the first person to file the Application;(the first official description of the invention, andnotice that a patent is being sought). However, inthe U.S.A. priority is awarded to the first to invent.

This is a subtle difference that requires scientists inthe U.S.A. to be good record keepers.

The documents that people call patents areusually the published Applications. Patentingorganisations publish Applications (the descriptionof the patents) 18 months after the first applicationdate (an important date also called the filing date orthe priority date), so that researchers have earlywarning of what is being sought for patenting.When the patent is eventually granted it may havebeen amended by the patentees. Only then can thelegal effect of the patent be determined.

Novelty and Inventiveness The invention to be patented has to meet stan-

dards of novelty and inventiveness, that is, itshould not be already in the public domain nor bean obvious variant of something that is known.

A patent (also called a specification) has twobasic parts: a description of the invention, possibly withdrawings or graphs, and the claims.While working examples of the invention are desir-able, they are not generally required.

The patenting process requires the Applicationto be lodged in a government patent office alongwith forms that name the owner of the patent andusually identify the inventor(s), and the patentingfee. The patent office will usually, but not always,carry out a search through prior documents inorder to establish that there is novelty and also aninventive step in the patent.

Countries of EnforcementA patent only has effect in the country granting

it. Thus, in order to protect an invention, it may benecessary to apply for a patent in a number of

DOI: 10.1595/147106705X45794

Patents and Copyright for ScientistsINTELLECTUAL PROPERTY COVERS PATENTS, COPYRIGHT, TRADE MARKS, INDUSTRIAL DESIGNSAND RIGHTS IN CONFIDENTIAL INFORMATION

By Ian WishartPatents Department, Johnson Matthey Technology Centre, Blounts Court, Sonning Common, Reading RG4 9NH, U.K.

E-mail: [email protected]

countries. This is conventionally done within 12months of the initial filing date (the priority date).Certain patent systems, such as PCT (PatentCooperation Treaty) or European Applications,can cover a number of countries.

Some patents can lead to confusion. For exam-ple, Japanese inventors apply for huge numbers ofpatents, but only about a quarter result in actualgranted patents. Frequently, a scientist or business-man may be inhibited by the existence of such apatent, but closer inspection could show that thepatent is only a Japanese Application, without legalstatus in countries outside Japan.

The Patent ClaimsThe claims of a patent govern the legal effect of

the patent, that is, the areas of technology that areto be monopolised. The accurate interpretation ofpatent claims is a skilled art, and an area in whichpatents professionals need to be consulted.However, a patent only protects against commer-cial activities, such as offering for sale, making,selling, etc., so this may not be necessary.Undertaking experimental work within the scopeof the patent to prove, disprove or develop thepatented invention is not prevented. Many scien-tists wrongly concentrate on the examples orspecific description, just as they would carefullyread the experimental sections of scientific papers.

Generally it can be said that a feature is not pro-tected unless that feature is claimed or covered bygeneral language in the claims. Of course, an earli-

er patent may protect that feature. It may be aninfringement of a patent to knowingly provideanother person with the means to infringe a patent.This is not direct infringement but contributoryinfringement.

Monopoly Aspects of a PatentThe monopoly granted by a patent is just one of

many possible reasons for applying for a patent.The patent owner may in fact be interested inallowing others to operate within the patent, forexample by having them pay a licence fee or royal-ty. A patent may also be used as a bargaining toolin negotiations, or it can act as a short-term barri-er to allow the patent owner to establish acommercial lead. Sales personnel often wish tohave a patent to show to customers, to establishthat a particular product is novel. But above all themain reason for patenting for many companies isto establish freedom to operate and to make surethat a competitor cannot patent a particular devel-opment, and use it to prevent the company fromcommercialising an invention it was first to devise.

Challenging PatentsIf a patent is considered likely to prevent a com-

pany from proceeding with commercialising a newproduct or process, there are actions that can betaken. First, the new product or process should becarefully compared to the patent claims to estab-lish if the process or product is the same as all theaspects of the claims. Care needs to be taken here,


Advice for Inventors on Applying for Patents• It is not recommended that an inventor writes his own patents. This is because it is too easyto make the mistake of limiting the scope of the patent or include other fundamental errors.• An employer will normally have an in-house patent attorney or will use an outside patentattorney.• An individual should find a patent attorney, and websites or the government Patent Officecan provide a list (lawyers do not generally have the technical background to adequately repre-sent a client in patent drafting). A patent attorney needs to understand the invention, and willask many questions.• The first Application is usually made in the inventors country of residence (for convenience).Overseas Applications, especially where translations are necessary, can be quite expensive, andan individual may be unable to fund this level of patenting.


as courts may decide that a difference is insignifi-cant.

The legal status of the patent should bechecked: that is: whether it exists in the relevantcountry, that all the renewal fees have been paid,and that the patent is not more than 20 years old.A discussion between the scientist or engineer anda patent attorney may identify a way around thepatent claim(s). Finally, if all of the above areunsuccessful, a study of the validity of the patentwill be required. Often, serious questions over theenforceability of the patent may arise from findinga prior document, or a prior commercial use thatwas not found during the patent examinationprocess. This can be a time-consuming and expen-sive procedure, and may not always lead to areliable conclusion.

Patent OwnerIt should be mentioned that the first owner of

an invention is the inventor(s) unless the owner-ship is transferred by a contract, or the inventionarose out of an employees duties. Most employedinventors will find that their contract of employ-ment claims inventions as the property of theemployer.

Patents Illustrate Technology ChangeAs an example of the development of patent-

ing, the field of the platinum group metals (pgms)has been analysed, see the block chart. This shows

the number of individual published Applicationslisting one of the six pgms in each recent decade.If two or more metals are listed, there are two ormore counts, but duplications of the same inven-tion have been eliminated. The current decadeshows lower numbers since it is only part waythrough. As can be seen, each decade has resultedin more patents for each metal, with patents forplatinum and palladium dominating.

Thus, patents play an important part in com-mercial activities, protecting intellectual propertyand establishing legal rights. The information theycontain and their effects are hugely important.

Glossary

PCT (Patent Cooperation Treaty) can cover almost everycountry in the World (designated by the Applicant).

European Applications/European Patents cover 30European countries, including Turkey.

0

5000

10000

15000

20000

25000

71/80 81/90 91/00 01/04

Os

Ir

Ru

Rh

Pd

Pt

The number of Applications naming the six platinumgroup metals that were granted in the three decadesbefore the millennium and for the current decade

Important Patents in the Platinum Group Metals Field

The following are the authors personal selec-tion of important pgms patents that have had aconsiderable effect on technology (1).

Early CatalysisIn the early part of the 19th century, the first

catalytic processes (although that term had onlybeen coined by Berzelius in 1836) were beingdeveloped by Kuhlmann in France, represented bythe platinum catalysed nitric acid and sulfuric acidprocesses in French Patents 11331 (Application filed1838) and 11332, respectively. These conceptstook some time to develop, until Ostwald (British

Patents 698 and 8300; 1902) and Kaiser (GermanPatent 271,517; 1909) established the bases of thehuge ammonia oxidation industry using platinumgauze catalysts. The similar industrial process formaking hydrogen cyanide was developed in the1930s by Andrussow (German Patent 549,055;1932).

Plating/ElectroplatingPlating of precious metals was of great interest

in the first half of the 19th century, but effectivemethods of plating pgms were only slowly devel-oped (in contrast to electroplating silver or gold).


Two key patents from that time are H. B. LeesonsBritish Patent 9374; 1842 and G. Howells BritishPatent 11,065; 1846.

RefiningDuring the 1920s, with the discovery of the

platinum-rich Merensky reef in South Africa, therewas considerable research into refining methodsAlan R. Powell and Ernest C. Deering, who bothworked for Johnson Matthey, developed the matteprocess for smelting. This was patented as BritishPatent 316,063; 1929.

Homogeneous and HeterogeneousCatalysis

In 1976 Geoffrey Wilkinson was awarded apatent (U.S. Patent 3,933,919) for the developmentof a rhodium-based homogeneous catalyst. This wasa truly major step in chemical process technology.

In heterogeneous catalysis, exhaust gas purifica-tion is a huge consumer of pgms. Once theincreasingly detrimental effects of car exhaustgases on the environment was recognised as an

issue, patenting activity increased. For example, seeJohnson Mattheys 1975 patent British Patent1,417,544. Johnson Matthey has also broughtpatented technology to the removal of soot fromdiesel exhausts (European Patent 341,832; 1989).

Biological UsesFinally, I mention the discovery of the biologi-

cal activity of platinum complexes. This led to anew and effective way of treating cancers. Theknown compound cisplatin was patented in U.S.Patent 4,177,263; 1979, and the second generationcompound carboplatin was patented in a numberof countries (e.g. British Patent 1,380,228; 1975).Incidentally, the cisplatin patent was applied forbefore that for carboplatin, but granted afterwards.This was because of the difficulty in persuading theU.S. Patent Office that a platinum compoundcould be an active anticancer agent.

Reference1 Donald McDonald and Leslie B. Hunt, A History

of Platinum and its Allied Metals, JohnsonMatthey, London, 1982

Another area of intellectual property that scien-tists come across in day-to-day work is copyright.Copyright automatically applies to original literaryor artistic work (regardless of merit) upon creation.Copyright is owned by the creator(s) unless thecreator is an employee, in which case copyright isowned by the employer. Scientific authors will beasked to transfer or assign copyright to a publish-er, to permit the publisher to print and publish apaper, otherwise this would technically be copy-right infringement. The better copyright transferspermit the author some rights to re-use the mater-ial in the paper.

Two important issues concerning copyrightneed to be mentioned. Recent changes inEuropean copyright law allow copying of articlesor parts of books only for research that is purelyacademic. A copyright fee is generally due forcopying for commercial research, even when theresearcher or employer already owns a copy.

The other issue concerns electronic copies.

Scanning copies is regarded in the same light asphotocopying.

The Internet is another minefield for users.Because an article or image is available on theInternet does not mean that it can be freely copied,forwarded, stored in a database or used in anotherpublication. The website concerned almost certain-ly will have a small print section with a copyrightnotice and conditions. As with patents, the com-plexities of copyright law warrant the use of aspecialist where there is any case of doubt.

The Author

Ian Wishart has the position of CorporatePatents & Licensing Director of JohnsonMatthey PLC, where he has worked since1987. After gaining a degree in ChemicalEngineering from Edinburgh University, hetrained in intellectual property, qualifyingas a U.K. Patent Attorney in 1973. He hasworked for Sandoz in Switzerland, and forthe U.K.’s National Coal Board, where hebecame involved in licensing and other IPagreement work.

Other Intellectual Property

CHEMICAL COMPOUNDSDimeric Palladium Complexes with Bridging ArylGroups: When Are They Stable?A. C. ALBÉNIZ, P. ESPINET, O. LÓPEZ-CIMAS and B. MARTÍN-RUIZ, Chem. Eur. J., 2005, 11, (1), 242252

[Pd2(µ-R)2(η3-allyl)2] (R = haloaryl, mesityl) wereprepared. The haloaryl complexes exchange betweentheir cis and trans isomers (relative to the orientationof the two allyl groups in the dimer) by solvent-assist-ed associative bridge splitting. Stable aryl bridges arefavoured by ancillary ligands of small size and lackingelectron lone pairs, and aryl ligands reluctant to beinvolved in homo and hetero CC coupling.

Synthesis, Structure and ElectrochemicalProperties of Tris-picolinate Complexes ofRhodium and IridiumS. BASU, S.-M. PENG, G.-H. LEE and S. BHATTACHARYA,Polyhedron, 2005, 24, (1), 157163

The pic ligands of [M(pic)3] (1) (M = Rh, Ir; Hpic =picolinic acid) are coordinated as bidentate N,O-donors. A water of crystallisation molecule is Hbonded to the carboxylate fragments of two adjacent(1) and acts a bridge between the individual (1). (1) arediamagnetic and show intense MLCT transitions inthe visible region. CV on (1) shows a M(III)M(IV)oxidation and a ligand-centred reductive response.

Iridium(I) and Rhodium(I) Cationic Complexeswith Triphosphinocalix[6]arene Ligands: DynamicMotion with Size-Selective Molecular EncapsulationY. OBORA, Y. K. LIU, L. H. JIANG, K. TAKENAKA, M. TOKUNAGAand Y. TSUJI, Organometallics, 2005, 24, (1), 46

The title complexes (1) exhibited dynamic behav-iour with size-selective molecular encapsulation.Variable-temperature 31P1H NMR measurementswere carried out in the presence of various molecules(1). (1) were divided into three groups, depending onthe maximum projection area of the solvent-accessi-ble surface, A: < 45 Å2, 4568 Å2, and > 68 Å2.Molecules with A of 4568 Å2 just fit in the cavityand slow the dynamic behaviour.

Synthesis and Derivatization of Iridium(I) andIridium(III) Pentamethyl[60]fullerene ComplexesY. MATSUO, A. IWASHITA and E. NAKAMURA, Organometallics,2005, 24, (1), 8995

Ir(η5-C60Me5)(CO)2 (1) was obtained from the reac-tion of K(C60Me5) with [IrCl(CO)2]2 in MeCN/THF.Oxidation of the Ir atom of (1) by I2 gave an Ir(III)complex, Ir(η5-C60Me5)I2(CO) (2). The iodo and car-bonyl ligands of (2) can be readily replaced by alkyl,alkynyl, phosphine, and isonitrile ligands. (2) may beused as catalysts for organic synthesis.

ELECTROCHEMISTRYElectrochemical Investigations of PlatinumPhenylethynyl ComplexesL. KONDRACHOVA, K. E. PARIS, P. C. SANCHEZ, A. M. VEGA, R.PYATI and C. D. RITHNER, J. Electroanal. Chem., 2005, 576,(2), 287294

Pt phenylethynyl complexes exhibited irreversibleoxidations in benzene/MeCN near +1.2 V vs.Ag|AgCl. However, trans-bis(tri-n-butylphosphine)bis(phenylethynyl)platinum(II) underwent reductionin THF at 2.786 V. Photophysical measurementsestablished that as the phenylethynyl chain lengthincreases, the absorbance wavelength increases. Theemission wavelength shows a weak but similar trend.

Controlled Growth of a Single PalladiumNanowire between Microfabricated ElectrodesM. A. BANGAR, K. RAMANATHAN, M. YUN, C. LEE, C.HANGARTER and N. V. MYUNG, Chem. Mater., 2004, 16, (24),49554959

Dimensionally controlled growth of a single Pdnanowire (1) between premicrofabricated Au elec-trodes was achieved using an electrochemicalmethod. (1) of 100 nm, 500 nm, and 1 µm wide and2.5 µm long channels (length-to-diameter ratio ~2.525) were grown. Current of 100 nA was used.

PHOTOCONVERSIONA Luminescent Pt(II) Complex with a Terpyridine-Like Ligand Involving a Six-Membered ChelateRingY.-Z. HU, M. H. WILSON, R. ZONG, C. BONNEFOUS, D. R.McMILLIN and R. P. THUMMEL, Dalton Trans., 2005, (2),354358

[Pt(1)Cl]+ (2) ((1) = 2-(8'-quinolinyl)-1,10-phenan-throline) was prepared. The six-membered chelatering in (2) gives relief to the angle strain as well assome non-planarity in bound (1). In CH2Cl2 (2) exhib-ited higher energy charge-transfer absorption, butslightly lower energy emission than [Pt(3)Cl]+ ((3) =2-(2'-pyridyl)-1,10-phenanthroline).

Electrochemical and Luminescent Properties ofNew Mononuclear Ruthenium(II) and BinuclearIridium(III)-Ruthenium(II) Terpyridine ComplexesN. YOSHIKAWA, T. MATSUMURA-INOUE, N. KANEHISA, Y. KAI,H. TAKASHIMA and K. TSUKAHARA, Anal. Sci., 2004, 20, (12),16391644

The title complexes include [RuII2Cl2(dpp)(terpy)2]2+

(1) and [IrIIIRuIICl2(dpp)(terpy)2]3+ (2) (dpp = 2,3-bis(2-pyridyl)pyrazine). The absorption spectra of (1)and (2) exhibit ligand-centred bands in the UV regionand MLCT bands in the visible region. The HOMOis based on Ru, and the LUMO is dpp-based.


ABSTRACTSof current literature on the platinum metals and their alloys

DOI: 10.1595/147106705X46496

Design of Novel Efficient Sensitizing Dye forNanocrystalline TiO2 Solar Cell; Tripyridine-thio-lato (4,4',4''-tricarboxy-2,2':6',2''-terpyridine)ruthenium(II)F. AIGA and T. TADA, Sol. Energy Mater. Sol. Cells, 2005, 85,(3), 437446

The title Ru complex (1) was designed based on theDFT MO calculations with PBE0 functional. (1) is amodification of the Ru black dye (2), with the NCSligands of (2) being replaced by C5H4NS ligands. (1)has a higher electron transfer rate from redox systemsto oxidised dyes and higher absorption efficiency tothe solar spectrum.

A Highly Efficient Redox Chromophore forSimultaneous Application in a PhotoelectrochemicalDye Sensitized Solar Cell and ElectrochromicDevicesA. F. NOGUEIRA, S. H. TOMA, M. VIDOTTI, A. L. B. FORMIGA, S.I. CÓRDOBA DE TORRESI and H. E. TOMA, New J. Chem., 2005,29, (2), 320324

Na6[RuII(dicarboxybipyridine)2Cl2(BPEB)] (1)(BPEB = trans-1,4-bis[2-(4-pyridyl)ethenyl]benzene)exhibits an electrochromic effect when reduced. Thecarboxylate groups of the bipyridine allow strongattachment to the surface of TiO2. This contributesto an efficient and reversible electron transfer fromthe oxide to the chromophoric ligand, colouring theoxide film blue. (1) also has a high photon-to-elec-tron conversion efficiency when applied as aphotoanode in a dye sensitised solar cell.

ELECTRODEPOSITION AND SURFACECOATINGSCharacterizations of Pd–Ag Membrane Preparedby Sequential Electroless DepositionW.-H. LIN and H.-F. CHANG, Surf. Coat. Technol., 2005, 194,(1), 157166

Sequential electroless plating on porous stainlesssteel was used to prepare Pd-Ag membranes. AFMestablished that lower skin layer roughness and lowerdeposition rate were related. EDS confirmed the Pd-Ag deposit over and inside of the porous substrate tobe homogeneous.

Preparation of Palladium and Silver AlloyMembrane on a Porous αα-Alumina Tube via aSimultaneous Electroless PlatingD. A. PACHECO TANAKA, M. A. LLOSA TANCO, S. NIWA, Y.WAKUI, F. MIZUKAMI, T. NAMBA and T. M. SUZUKI, J. MembraneSci., 2005, 247, (12), 2127

For the title process, seeding of Pd nanoparticles(1) on an α-Al2O3 tube allowed codeposition of Pdand Ag. (1) were distributed by dip-coating with Pdacetate or [Pd(acac)2] in organic solvents followed byreduction with alkaline hydrazine solution. Aftersimultaneous deposition, alloying of Pd and Ag wascarried out at 500ºC for 4 h in H2.

Morphological Evolution of the Self-AssembledIrO2 One-Dimensional NanocrystalsR.-S. CHEN, H.-M. CHANG, Y.-S. HUANG, D.-S. TSAI and K.-C.CHIU, Nanotechnology, 2005, 16, (1), 9397

The morphological evolution of IrO2 1D nanocrys-tals (1) via MOCVD has been observed. (1) resultfrom a decrease in the degree of interface instability.(1) occur from triangular/wedged nanorods viaincomplete/scrolled nanotubes to square nanotubesand square nanorods. The polycrystalline films com-posed of continuous 3D grains belong to the moststable form as compared to the 1D nanocrystals.

Thermophysical Properties and Deposition of B2Structure Based Al–Ni–Ru–M AlloysI. VJUNITSKY, P. P. BANDYOPADHYAY, St. SIEGMANN, M.DVORAK, E. SCHÖNFELD, T. KAISER, W. STEURER and V.SHKLOVER, Surf. Coat. Technol., 2005, 192, (23), 131138

The normal value range for the thermal conductiv-ity of the title alloys is 1020 W m1 K1 at roomtemperature, but can be reduced to ~ 3.5 W m1 K1

by modifying the alloy composition. A fused and sub-sequently pulverised Al-Ni-Ru alloy was deposited ona Ni-based superalloy (modified CMSX-4) using vac-uum and atmospheric plasma spraying. The coatingshad favourable coatingsubstrate adhesion. A segre-gated intermetallic phase was detected at theAl50Ni40Ru10/modified CMSX-4 interface.

APPARATUS AND TECHNIQUEFabrication and Characterisation of Ultra-ThinTungsten–Carbon (W/C) and Platinum–Carbon(Pt/C) Multilayers for X-Ray MirrorsB. K. GAN, B. A. LATELLA and R. W. CHEARY, Appl. Surf. Sci.,2005, 239, (2), 237245

Ultra-thin Pt/C and W/C multilayer films (1) werefabricated using DC magnetron sputtering. The bilay-er period and the total number of layers were variedto ascertain the X-ray reflectance response. XPSestablished that a distinct intermixing layer developsin (1). (1) are mechanically reliable and have excellentadhesion. Hardness and Youngs modulus improvedwith increasing number of layers. (1) have potential asmirrors for high energy X-ray applications.

Morphological Study of Supported Thin Pd andPd–25Ag Membranes upon Hydrogen PermeationY. ZHANG, M. KOMAKI and C. NISHIMURA, J. Membrane Sci.,2005, 246, (2), 173180

H2 permeation of Pd and Pd-25Ag membranessupported by V-15Ni was investigated at 423673 K.The Pd-25Ag membrane was more resistant to H-induced cracking and grain growth. H permeation ofthe Pd-25Ag/V-15Ni membrane (1) was carried outat 573 and 673 K for 200 h. At 573 K, small amountsof oxide formed on the Pd-Ag surface. Whisker andfissure-oxide morphologies were dominant on theexit and entrance side of (1), respectively, along withsevere metallic interdiffusion, at 673 K.



HETEROGENEOUS CATALYSISPreparation and Characterisation of Pt ContainingNbMCM-41 Mesoporous Molecular SievesAddressed to Catalytic NO Reduction byHydrocarbonsI. SOBCZAK, M. ZIOLEK and M. NOWACKA, MicroporousMesoporous Mater., 2005, 78, (23), 103116

The title catalysts were prepared via impregnationof NbMCM-41 with Pt(NH3)4(NO3)2 or H2PtCl6 (1wt.% of Pt). Smaller size Pt clusters were obtainedwith H2PtCl6. A FTIR study with NO + O2 + C3H6

indicated that Pt/NbMCM-41 has potential for theSCR process. The NbO species enhance the oxida-tive activity in NO → NO2, whereas the Pt species isresponsible for hydrocarbon activation. NbMCM-41acts as storage for the nitrate/nitrite species.

Flame-Made Pd/La2O3/Al2O3 Nanoparticles:Thermal Stability and Catalytic Behavior inMethane CombustionR. STROBEL, S. E. PRATSINIS and A. BAIKER, J. Mater. Chem.,2005, 15, (5), 605610

Flame spray pyrolysis was used to prepare Pdnanoparticles (< 5 nm) supported on La-stabilisedAl2O3 (1) with specific surface areas of 50180 m2 g1.(1) was tested for the catalytic combustion of CH4. (1)exhibited excellent thermal stability in terms of spe-cific surface area up to 1200ºC and retarded γ- toα-Al2O3 transformation. (1) was tested as-preparedand after sintering at 1000ºC (Pd particles, 50150nm). All the materials exhibited similar catalytic per-formance after an initial conditioning cycle if thetemperature was cycled several times (2001000ºC).

Effect of the Promoter and Support on theCatalytic Activity of Pd–CeO2-Supported Catalystsfor CH4 CombustionG. PECCHI, P. REYES, R. ZAMORA, T. LÓPEZ and R. GÓMEZ, J.Chem. Technol. Biotechnol., 2005, 80, (3), 268272

Pd-CeO2-supported catalysts, prepared by the sol-gel technique, were used for the catalytic combustionof CH4. The addition of CeO2 to Al2O3 gave a highlydispersed catalyst when compared with their ZrO2

counterparts. However, the catalytic activity of thePd-CeO2-ZrO2 series is higher, due to the Pd havinga larger particle size.

The Oxidation of Water by Cerium(IV) Catalysedby Nanoparticulate RuO2 on Mesoporous SilicaN. C. KING, C. DICKINSON, W. ZHOU and D. W. BRUCE, DaltonTrans., 2005, (6), 10271032

Mesoporous silicates were prepared by templatingon the hexagonal mesophase of bis(2,2'-bipyri-dine)(4,4'-dinonadecyl-2,2'-bipyridine)ruthenium(II)dichloride using liquid-crystal templating. On calcina-tion, the surfactant template was removed, except forthe central Ru ion that was oxidised to RuO2

nanoparticles (1) within the pores. (1) were active incatalysing the oxidation of H2O by acidic CeIV.

HOMOGENEOUS CATALYSISPd Nanoparticle Aging and Its Implications in theSuzuki Cross-Coupling ReactionJ. HU and Y. LIU, Langmuir, 2005, 21, (6), 21212123

The Pd nanoparticles (1) recovered from the N,N-dihexylcarbodiimidePd nanoparticle compositecatalysts used in Suzuki cross-couplings, were foundto transform from spherical-shape to larger needle-shaped crystals. (1) aggregated into nanosizedblackberry-like assemblies (100200 nm) as a resultof Ostwald ripening. In a second type of ripening,atomic rearrangement occurred and (1) transformedinto needle-shaped nanocrystals. These observationswill be important for the future design and optimisa-tion of durable nanoparticle catalysts.

Pd(II)-Biquinoline Catalyzed Aerobic Oxidation ofAlcohols in WaterB. P. BUFFIN, J. P. CLARKSON, N. L. BELITZ and A. KUNDU, J.Mol. Catal. A: Chem., 2005, 225, (1), 111116

Pd(OAc)2 stabilised by 2,2'-biquinoline-4,4'-dicar-boxylic acid was used in the aerobic oxidation ofprimary and secondary alcohols. H2O was used as thereaction solvent, with air as the oxidant. Aliphatic pri-mary alcohols were fully oxidised to carboxylic acidproducts. Secondary alcohols gave the correspondingketones. The catalyst can be recycled.

New Carbazole–Oxadiazole Dyads forElectroluminescent Devices: Influence of AcceptorSubstituents on Luminescent and ThermalPropertiesK. R. J. THOMAS, J. T. LIN, Y.-T. TAO and C.-H. CHUEN, Chem.Mater., 2004, 16, (25), 54375444

Oxadiazole-incorporated carbazoylylamines (1)were synthesised using Pd catalysed CN couplingreactions with Pd(dba)2/P(t-Bu)3 catalyst and t-BuONa base. The reactions were best carried out intoluene at 80ºC. Yields of (1) ranged from 7595%.(1) were purified by reprecipitating twice fromCH2Cl2/MeOH before application in the electrolumi-nescent devices, such as OLEDs.

Hydroformylation of 1-Hexene in Ionic LiquidsCatalyzed by Highly Active Rhodium-PhosphineComplexesH. ZHENG, M. LI, H. CHEN, R. LI and X. LI, Chin. J. Catal., 2005,26, (1), 46

The hydroformylation of 1-hexene catalysed byHRh(CO)(TPPTS)3 complexes (1) (TPPTS = triph-enylphosphine-m-trisulfonic acid trisodium salt) wascarried out in 1-butyl-3-methylimidazolium tetrafluo-roborate ([bmim]BF4). The activity and selectivity of(1) in [bmim]BF4 were higher than those in otherionic liquids. The TOF of 1-hexene and selectivity foraldehyde were 1508 h1 and 92%, respectively, underoptimum conditions. The high activity of (1) is due toits higher solubility in [bmim]BF4 and to the absenceof halide ions.

Mononuclear Ruthenium Catalysts for the DirectPropargylation of Heterocycles with PropargylAlcoholsE. BUSTELO and P. H. DIXNEUF, Adv. Synth. Catal., 2005, 347,(23), 393397

While [(p-cymene)RuCl(PR3)][OTf] (PR3) (PR3 =PCy3, PPh3) catalyse the propargylation of furan or 2-methylfuran by the alkynol HC≡CCH(OH)Ph inmoderate yield, [(p-cymene)RuCl(CO)(PR3)][OTf] aremore active. The stoichiometric reaction of [(p-cymene)RuCl(PR3)][B(ArF)4] (ArF = 3,5-(CF3)2C6H3)and the alkynol resulted in the in situ formation, viaallenylidene and hydroxycarbene intermediates, of[(p-cymene)RuCl(CO)(PR3)]B(ArF)4].

An Efficient Catalytic Asymmetric Route to 1-Aryl-2-imidazol-1-yl-ethanolsI. C. LENNON and J. A. RAMSDEN, Org. Process Res. Dev., 2005,9, (1), 110112

Catalytic asymmetric transfer hydrogenation of 1-aryl-2-imidazol-1-yl-ethanones with formic acid using[(R,R)-TsDPEN]Ru(Cymene)Cl gave homochiral 1-aryl-2-imidazol-1-yl-ethanols. The hydrogenation wascarried out under mild conditions at a molar sub-strate-to-catalyst ratio of 10002000. BisphosphinoRu diamine complexes were found to be ineffective.

FUEL CELLSHigh-Temperature Polymer Electrolytes for PEMFuel Cells: Study of the Oxygen ReductionReaction (ORR) at a Pt–Polymer ElectrolyteInterfaceZ. LIU, J. S. WAINRIGHT and R. F. SAVINELL, Chem. Eng. Sci.,2004, 59, (2223), 48334838

A micro-band electrode cell was used to investigatethe ORR for a Pt/polybenzimidazolephosphoricacid system. The obtained Tafel plots were linearover four orders of magnitudes of kinetic currentdensity. Both the kinetic parameters and the masstransport data were comparable to those of aPt/phosphoric acid system.

Effects of Preparation Conditions on Performanceof Carbon-Supported Nanosize Pt-Co Catalysts forMethanol Electro-Oxidation under AcidicConditionsJ. ZENG and J. Y. LEE, J. Power Sources, 2005, 140, (2), 268273

Pt/C and Pt-Co/C were prepared by NaBH4 reduc-tion of metal precursors. Citric acid was used as thecomplexing agent. The largest Pt-Co particles (12nm) were formed in alkaline solution and the small-est particles (3.7 nm) in unbuffered solution. XPSshowed that Pt is in the metallic state, whereas mostof the Co is oxidised. The performance of the Pt-Co/C catalysts in MeOH electrooxidation underacidic conditions showed improvements over thePt/C catalyst in both activity and CO-tolerance dueto the Co addition.

Catalytic Activity of Pt–Ru Alloys Synthesized by aMicroemulsion Method in Direct Methanol FuelCellsL. XIONG and A. MANTHIRAM, Solid State Ionics, 2005, 176,(34), 385392

A microemulsion method was used to preparenanostructured Pt-Ru/C catalysts (1) with differentparticle sizes. The electrochemical performances of(1) were evaluated in half cells with a mixture of 1 MH2SO4 and 1 M MeOH and in single cell DMFCs. (1)prepared with a water to surfactant molar ratio (W) of10 exhibited the maximum mass activity with theleast charge transfer resistance at an optimum particlesize of ~ 5.3 nm. The mass activity decreases and thecharge transfer resistance increases as the value of Wdecreases or increases from 10.

The Behavior of Palladium Catalysts in DirectFormic Acid Fuel CellsY. ZHU, Z. KHAN and R. I. MASEL, J. Power Sources, 2005, 139,(12), 1520

Pd-based anode catalysts were used in DFAFCs.Power densities of 255 to 230 mW cm2 wereachieved at relatively high voltages of 0.40 to 0.50 Vin formic acid (3.0 to 15.0 M) at 20ºC. A MEA witha Pd catalyst gave some decay in fuel cell perfor-mance over several hours. However, the performancecan be completely recovered by applying a positivepotential at the anode.

ELECTRICAL AND ELECTRONICENGINEERINGOn the Perpendicular Anisotropy of Co/PdMultilayersJ. I. HONG, S. SANKAR, A. E. BERKOWITZ and W. F. EGELHOFF,J. Magn. Magn. Mater., 2005, 285, (3), 359366

Co/Pd multilayers were deposited both at roomtemperature when thermally activated interfacialintermixing augmented the intentional alloying, andat 77 K. Stressed interfacial alloying is the dominantmechanism. Low temperature measurements indicat-ed the presence of polarised Pd. The hard-axismagnetisation was modelled with a distribution oflocal perpendicular anisotropies which reflect localcomposition variations.

Synthesis and Characterization of CaRuO3 andSrRuO3 for Resistor Paste ApplicationK. GURUNATHAN, N. VYAWAHARE and D. P. AMALNERKAR, J.Mater. Sci.: Mater. Electron., 2005, 16, (1), 4753

Ca and Sr ruthenates (1) were prepared by air heat-ing admixtures of the respective carbonates of Ca/Srand RuO2 at 500, 800 and 900ºC for 15 h. The solid-state reactions occurred at 700800ºC. Thesepowders still contained carbonate and hence wereheated again at 900ºC for 15 h to eliminate the car-bonate. The average particle size of (1) is ~ 200400nm. The resistor paste was formulated using (1) pre-pared at 800 or 900ºC and heat treated at 900ºC.


METALS AND ALLOYSAlloys for High Temperature ApplicationsGENERAL ELECTRIC CO European Appl. 1,505,165

An alloy (1) for use in high temperature applicationscomprises (in at.%): ≥ ~ 50 Rh; ≥ ~ 5 of Pt and/orPd; ~ 524 Ru; and ~ 140 Cr. (1) contains ≤ ~ 50%by vol. of an A3-structured phase which quantity isdefined by: ([Cr] + 2[Ru]) is ~ 2550%, and [Ru] and[Cr] are at.% of Ru and Cr, respectively. (1) is used forrepairing articles, such as gas turbines, etc.

Modified High Strength Single Crystal SuperalloyD. P. DeLUCA et al. U.S. Appl. 2005/016,641

A single crystal Ni base superalloy (1) contains (inwt.%): 312 Cr, ≤ 3 Mo, 310 W, ≤ 5 Re, 612 Ta,47 Al, ≤ 15 Co, ≤ 0.05 C, ≤ 0.02 B, ≤ 0.1 Zr, ≤ 0.8Hf, ≤ 2.0 Nb, ≤ 1.0 V, ≤ 0.7 Ti, ≤ 10 of Ru, Rh, Pd,Os, Ir, and/or Pt, with the balance being Ni. (1) ispore-free and eutectic γ-γ' free and has a γ' morphol-ogy with a bimodal γ' distribution.

APPARATUS AND TECHNIQUEPt-MOx for Dye-Sensitised Solar CellKWANGJU INST. SCI. TECHNOL. U.S. Appl. 2005/016,586

A counter electrode (1) for a dye-sensitised solar cell(2) is made by co-sputtering Pt and a metal oxide(MOx) as target materials to deposit nanocrystallinePt and amorphous metal oxide on the substrate. MOxis selected from Ru, Ti, etc., with electrical conductiv-ity ≥ 0.1 S m1 and refractive index of ≥ 2. (1) exhibitsimproved performances as an electrocatalyst used inthe reduction of I3

during operation of (2).

Plasma Display Panel and DeviceNEC CORP U.S. Appl. 2005/035,714

A plasma display panel has discharge cells formedbetween the front substrate and rear substrate, andelectrodes (1) separated by partition walls (2). Anelectrode material (3) used to form (1) comprises: aconductive paste or sheet containing conductive par-ticles of Pt, Pd, Ru, Ag, Au, etc., and glass borosilicatefrit. (3) has sandblast resistance which is higher afterbaking than that of (2). (3) is capable of preventingdamage to (1) caused by a sandblast process while (2)are formed.

Organic Electroluminescent ElementDAINIPPON INK CHEM. INC Japanese Appl. 2004-253,371

An organic electroluminescent element (1) compris-es a luminous layer (2) between a positive electrodelayer and a negative electrode layer formed on a trans-parent substrate. (2) contains a phosphorescentmaterial made of an Ir(III) complex (3), and a parti-tion wall layer. (3) contains a bidentate ligand, with aH atom or an alkoxyl group with 110 C atoms. (1) ismade by wet film forming and has high luminous effi-ciency and high luminance.

Hydrogen Occlusion CompositesTOYOTA MOTOR CORP Japanese Appl. 2004-261,739

A H occlusion material capable of occluding andreleasing H at room temperature and atmosphericpressure comprises a C material with fine pores thatare filled with a H occlusion alloy (1). The pore edgesof the C support Pd and/or V, which have an occlu-sion pressure higher than that of (1).

HETEROGENEOUS CATALYSISDiesel Particulate FilterHALDOR TOPSOE A/S European Appl. 1,493,484

Catalytic purification of exhaust gas from a dieselengine occurs by passing the exhaust gas through awall flow filter containing a material (1) catalyticallyactive in the reduction of NOx to N2 and the oxida-tion of carbonaceous compounds to CO2 and H2O.(1) comprises: Pd 0.251 g l1 filter, Pt ≤ 2 g l1 filter,V2O5 and WO3. The wall flow filter is made of sin-tered SiC particles having a surface layer of TiO2.

Intermediates for Acetyl Cholinesterase Inhibitors HETERO DRUGS LTD World Appl. 2005/003,092

A simple and cost effective industrial process forpreparing intermediates of acetyl cholinesteraseinhibitors is provided. For example, 5,6-dimethoxy-2-(4-pyridyl)methyl-1-indanone is hydrogenated usingPt oxide catalyst in the presence of HCl acid under 2bars of pressure to give 4-[(5,6-dimethoxy-1-indanon)-2-yl] methylpiperidine hydrochloride (1).Pd/C, Raney Ni or Ru oxide catalyst can also be usedunder 110 bars of H2. (1) is converted to donepezilhydrochloride, an acetyl cholinesterase inhibitor.

Exhaust Gas Purification from a Lean Burn EngineJOHNSON MATTHEY PLC World Appl. 2005/016,496

A catalyst structure for treating exhaust gas from alean burn internal combustion engine comprises asubstrate monolith of a lean NOx catalyst (LNC)composition associated with at least one partial oxi-dation catalyst (POC). The LNC composition isselected from: (a) Ag/Al2O3; and (b) metal(s) of Cu,Fe, Co and Ce supported on at least one zeolite.The POC is selected from: (i) a bulk oxide(s) of Mn,Fe, Ce and Pr; and (ii) Rh and/or Pd disposed oninorganic oxide support(s).

High-Activity Isomerisation CatalystUOP LLC U.S. Appl. 2005/027,154

A highly active isomerisation catalyst and process isdisclosed for selective upgrade of a paraffinic feed-stock to an isoparaffin-rich product for blending intogasoline. The catalyst support is a sulfated oxide orhydroxide of a Group IVB metal, with a first catalystcomponent of at least one lanthanide element or Ycomponent, preferably Yb, and at least one Pt groupmetal component, preferably Pt, and a refractoryoxide binder with dispersed Pt group metal(s).


NEW PATENTS

DOI: 10.1595/147106705X46414

HOMOGENEOUS CATALYSISHydrogenation of Carboxylic AcidsDAVY PROCESS TECHNOL. LTD European Appl. 1,499,573

A homogeneous process for the hydrogenation ofcarboxylic acids and/or their derivatives is carried outin the presence of a catalyst (1) comprising Ru, Rh,Os, Pd or Fe, and an organic phosphine, such as tris-1,1,1-(diphenylphosphinomethyl)ethane, with ≥ 1wt.% H2O. (1) can be regenerated in H2 and H2O.H2O acts as the solvent, so does not need removingfrom any reactant before the start of the reaction.

Production of Chlorotris(triphenylphosphine)Rh(I) W. C. HERAEUS GmbH World Appl. 2005/005,448

Chlorotris(triphenylphosphine)Rh(I) (1) is pro-duced by reacting a RhCl3 solution withtriphenylphosphine in mixtures of C2C5 alcoholsand H2O, followed by cooling and filtering of theresultant crystalline precipitate. The mixture of reac-tants is heated to ~ 75ºC and is then maintained at80110ºC. The method leads to increases in the yieldand the quality of the resultant crystals of (1).

Carbonylation of Conjugated DienesDSM IP ASSETS BV World Appl. 2005/014,520

A continuous process for the carbonylation ofbutadiene proceeds by reacting the butadiene withCO and a hydroxyl group-containing compound inthe presence of a Pd catalyst system (1) in a reactionzone to form a reaction mixture. (1) comprises: (a) asource of Pd cations; (b) a mono-, bi- or multidentatephosphine ligand containing P atom(s) directlybound to 2 or 3 aliphatic C atoms, as the process lig-and (2), to give a Pd-phosphine ligand complex; and(c) a source of anions containing a carboxylic acidand halide ions. The process gives improved stability.(2) is fed continuously or periodically to the process.

Catalysts with N-Heterocyclic Carbene LigandsMERCK PATENT GmbH World Appl. 2005/016,522

Immobilisable Ru catalysts (1) have N-heterocycliccarbene (NHC) ligands comprising a SiR'n(OR')3ncarrying group on one of the two N atoms of theNHC ligand. (1) are used as homogeneous catalysts inCC coupling reactions, especially in olefinicmetathesis. The invention further relates to the use ofthese compounds as starting materials for producinganalogue (1) catalysts having NHC ligands.

Optically Active Amine ProductionTAKASAGO INT. CORP Japanese Appl. 2004-256,460

An optically active amine compound (1) is preparedin high yields and stereoselectivities by asymmetrichydrogenation of the corresponding amine in thepresence of an Ir complex catalyst. The catalyst is[IrX(H)(Y)(L)]; X is Br or I; Y is an organic acidresidue; and L is an optically active compound thatcan coordinate with the Ir atom, such as (S)-BINAP.The reaction proceeds without additives. (1) is usefulas an intermediate for synthesising various com-pounds, particularly for pharmaceutical preparations.

FUEL CELLSFuel Cell Electrode with High Catalyst Utilisation TOYODA CHUO KENKYUSHO KK U.S. Appl. 2005/019,650

One side of a C paper electrode diffusion layer issoaked in a Teflon® dispersion solution and put intocontact with a solution containing H2PtCl6 and ani-line (1) and a graphite counter-electrode. Electricalcurrent is applied; (1) is polymerised to a Pt-polyani-line (2) layer. The Pt is reduced to make an electrode.Two of these Pt electrodes are used to form a smallfuel cell with (2) on the inside, next to Nafion®.

Organic Platinum Group Element of FullerenolHONJO CHEMICAL CORP Japanese Appl. 2004-217,626

An organic Pt group element compound (1) is usedas the catalyst in fuel cell electrodes. These compriseproton conductive C clusters of fullerenol (2) and/orfullerenol hydrogen sulfate ester (3) with Pt or Pdbonded to the C atoms. (1) is produced by reacting(2) and/or (3) with a zerovalent complex of a Pt groupelement, such as bis(dibenzylidene)Pt(0). (1) is a pro-ton conductor; Pt/Pd is dispersed at the atomic level.

ELECTRICAL AND ELECTRONICENGINEERINGPalladium Complexes for Printing CircuitsHEWLETT PACKARD DEV. CO World Appl. 2005/010,108

A stable ink-jettable composition includes a Pdaliphatic amine complex (1) solvated in a liquid vehi-cle. (1) is used in electronic devices by jetting onto avariety of substrates in a predetermined pattern. Asecond composition contains a reducing agent, suchas formic acid, and is also applied to the substrate byink-jet printing. It reduces (1) to Pd metal on heating.

Current Perpendicular to the Planes SensorHITACHI GLOB. STORAGE TECHNOL. U.S. Appl. 2005/024,790

A magnetic read head has a current perpendicularto the planes (CPP) sensor with a highly conductivetop cap layer of Ru or Rh, or a top cap layer structurewhich includes a first Ta layer only, a second layer ofRu, Rh or Au with the first layer located between aspacer layer and the second layer. The CPP sensorfurther comprises: a ferromagnetic pinned layerstructure and a free layer structure, with a nonmag-netic spacer layer located between.

Weak Inversion Mode MOS Decoupling CapacitorINTEL CORP U.S. Patent 6,849,909

A method and apparatus for a weak inversion modeMOS decoupling capacitor is described, embodied byan enhancement-mode p-channel MOS transistor (1).The gate material of (1) is PtSi or Ta nitrate, Ir, Niand As, with work function < 0.56 V. The thresholdvoltage of (1) is changed by modifying the substratedopant levels. The flat band magnitude of (1) is shift-ed by the changed materials. When (1) is connectedwith the gate lead connected to the positive voltage,the other leads are connected to the negative voltagean improved decoupling capacitor results.


This is the final article in a short series examin-ing ways of looking after thermocouples (13).

A thermocouple converts a temperature differ-ence into a voltage which is converted into areading by a temperature indicator. The voltage isgenerated by the lengths of wire in the temperaturegradient between the hot junction in the furnaceand the cold junction at the indicator. In practice,the temperatures between the indicator and thefurnace wall are low and the gradients are small.To reduce costs these lengths of thermocouplewire are replaced by base metal compensatingwire, connected at the thermocouple head.

Compensating wires should generate the samevoltage as the thermocouple wires they replace.(The indicating instrument corrects for the differ-ence between its terminal temperature and thestandard cold junction temperature of 0ºC.) Userscan choose wire grades A or B (4) to replace ther-mocouple wire Types R (Pt versus 13RhPt) and S(Pt versus 10RhPt). Grade A has an error of ≤ 30µV (equivalent to ≤ 2.6ºC at 1000ºC), with a max-imum operating temperature of 100ºC. Grade Bhas a maximum permitted error of ± 60 µV buthas suitable insulation for use up to an operatingtemperature of 200ºC.

The compensating wires used for Types R or Sare very similar: pure copper for the positive limband 0.6%NiCu for the negative one. The interna-tional standard for insulation colour codingspecifies orange for the outer insulation, orangefor the positive and white for the negative. (Thesuperseded U.K. standard (5) specified a greenlead with white to code for the positive wire.Green is now used for Type K leads.)

Thermocouple Types R and S, made to eitherthe International Practical Temperature Scale of1968 (IPTS-68) or the International TemperatureScale of 1990 (ITS-90), can use the same compen-sating wire, as their voltage outputs differ by only2 µV at 100ºC and 28 µV at 200ºC.

Type B (6RhPt versus 30RhPt) thermocouplesrequire only connecting, rather than compensating,

leads because the output is low at low tempera-tures. Using copper lead, with the thermocouplehead at 80ºC, reduces the output by 17 µV, equiv-alent to an error of only 1.9ºC when measuring1000ºC. However, the error will increase to 10ºCif the head is at 150ºC. The connecting wiresshould be colour coded grey and white (to lessenrisk of connection to a mains voltage supply).

To check a Type R or S compensating circuit,link the limbs at the thermocouple head the indi-cator should then show the head temperature; thiscan be independently verified. Alternatively, dis-connect the lead from the head, twist thecompensating wires together to form a hot junc-tion and place in boiling water, the indicatorshould show close to 100ºC.

Potential errors, when the head is at 80ºC, theindicator terminals at 30ºC and the hot junction at1000ºC are:(a) Type R used with copper cable under-reads by330 µV (25ºC).(b) Type R used with compensating lead with thepolarity reversed under-reads by 660 µV (50ºC).(c) Type R used with Type K cable reads high by+1734 µV (+130ºC).(d) Type B used with Type R/S compensating leadreads high by +311 µV (+34ºC).

Minimising the head temperature by carefullocation, radiation shields or forced cooling, willkeep the compensating wires within their operat-ing range. Correctly used, compensating leadsoffer significant cost saving with only a smallimpact on measurement accuracy.

References1 R. Wilkinson, Platinum Metals Rev., 2004, 48, (2), 882 R. Wilkinson, Platinum Metals Rev., 2004, 48, (3), 1453 R. Wilkinson, Platinum Metals Rev., 2005, 49, (1), 604 IEC 60584-3 Ed. 1.0 b.,1989-08-155 BS 1843:1952

The AuthorRoger Wilkinson is a Principal Metallurgist at Johnson MattheyNoble Metals in Royston, U.K. He has worked with platinumthermocouples since 1987 in manufacturing, calibration andcustomer technical support.


FINAL ANALYSIS

Thermocouples Compensating Circuits

DOI: 10.1595/147106705X46504

platinum metals reviewplatinum-clad base metal stirrers for many years molybdenum has been used as...

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