methanol catalyst poisons - a literature study (ccs)

8/10/2019 Methanol Catalyst Poisons - A Literature Study (CCS)

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Clean Hydrogen-rich Synthesis GasContract No: SES6-CT-2004-502587

Report No: CHRISGAS March 2009_WP3_D14

Deliverable Number D14

Budgetary Assessment of Post-CHRISGASTransportation Fuel Installation

Part 1 - Methanol Catalyst Poisons: A Literature Study

Work Package:3aTask:3a.4: Costing of Gas Upgrading Equipment

Contributing & Responsible Partner: CCS

Distribution: PublicDate: March 2009

Revision history:

Rev. no. Date Change information

0


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Methanol catalyst poisons

A literature study

ReportIND07002

06.25 Chrisgas

Versie 1.1

Authors: M. Rep, R.L. Cornelissen, S. Clevers

Deventer, May 2007

CCS B.V.

Energie-advies

Welle 36

7411 CC Deventer

tel. 0570-667000fax 0570-667001

[email protected]


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Report No: CHRISGAS_May 2007_WP3a_


2

Contents

Summary 3

1 Introduction 4

1.1 Methanol utilisation and market value 41.2 Methanol production and reaction conditions 51.3 Industrial methanol catalysts 61.4 Methanol reactor types 7

2 Potential methanol catalyst poisons 82.1 Sulphur compounds 92.2 Halogen compounds 102.3 Nitrogen compounds 102.4 Phosphorus compounds 112.5 Metallic compounds 112.6 Steam 122.7 Lubricating oil 132.8 Industrial removal of poisons from syngas feed 132.9 Conclusions 13

3 Further recommendations 15

Glossary 16

References 17


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Summary

The EU project Chrisgas 1aims at the production of a clean hydrogen-rich synthesis gasfrom biomass in the wood gasification plant in Vrnamo, Sweden. The gasification planthas an hourly throughput of maximum 4 ton biomass per hour. The hydrogen-rich

synthesis gas can subsequently be used for the production of methanol, dimethyl ether,hydrodgen,Fischer Tropsch diesel and other chemicals.

The task of CCS is to make the design for the methanol plant. The design will include the

methanol reactor and the distillation train downstream of the methanol reactor.

Methanol is produced from syngas using a state-of-the-art Cu/ZnO catalyst on an

aluminaoxide support. During the project meeting in Vrnamo of February 5th, 2007, theneed to investigate possible methanol catalyst poisons was discussed. Possible catalystpoisons include sulphur compounds, chlorine containing compounds and alkali metals.This report will describe known methanol catalyst poisons as well as how to treat the gas

upstream.

1Chrisgas: Acronym for Clean Hydrogen-rich Synthesis Gas


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1 Introduction

1.1 Methanol utilisation and market valueMethanol is primarily used to produce formaldehyde, methyl tertiary butyl ether (MTBE)

and acetic acid, with smaller amounts going into the manufacture of dimethyl

terephthalate (DMT), methylmethacrylate (MMA), chloromethanes, methylamines, glycolmethyl ethers, and fuels. It also has many general solvent and antifreeze uses, such asbeing a component for paint strippers, car windshield washer compounds and a de-icerfor natural gas pipelines.

In 2004, around 34% of global methanol is used to produce formaldehyde, 21% forMTBE and other fuel additives, and 9% for acetic acid. MTBE's share has been declining

following the decision to phase out its use in California and other states in the US.However, increased use in eastern and central Europe and Asia could partly compensate.Methanol used in the production of DMT is declining as purified terephthalic acid (PTA)

gains share in the polyester market (although partly offset by increased acetic acidconsumption in PTA manufacture).

However, a number of new applications for methanol are envisaged, especially as the

cost of production can be reduced by installing production facilities consuming low costnatural gas in the Middle East. For example, it could be used to make ethylene andpropylene, dimethyl ether as a substitute for diesel fuel, in hydrogen production insteadof naphtha, and in power generation. The development of methanol fuel cells, for

automotive, stationary power and portable electronic equipment applications, couldprovide a boost to consumption later this decade.

The European methanol contract value for the first quarter of 2007 (dated March 16,2007), was as high as 420 /ton (550 $/ton) fob 2. [1] However, spot prices havedeclined in the 2nd quarter of 2007 to below 250 /ton. It is expected as contractnegotiations for the 2ndquarter of 2007 have begun at less than 300 /ton market prices

have had their highest point. The development of the methanol market value (contractand spot prices) since 1998 are shown in figures 1.1 and 1.2.

Figure 1.1: Methanol contract prices in Western Europe, USA and Asia.

2fob: free on board; It means that the seller pays for transportation of the goods to the port of shipment, plus loadingcosts. The buyer pays freight, insurance, unloading costs and transportation from the port of destination to the factory.

The passing of risks occurs when the goods pass the ship's rail at the port of shipment.


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Figure 1.2: West European, US and Asian methanol spot prices.

1.2 Methanol production and reaction conditionsMethanol, a C1-molecule, is mainly produced from synthesis gas and is the simplest ofthe series of aliphatic alcohols. Methanol, or wood alcohol, is produced by thehydrogenation of carbon oxides over a suitable catalyst, according to the followingreactions:

Typical reaction conditions are a temperature of 200 - 300 C and a pressure of 5 - 11MPa. Because the volume of the products is less than the volume of the reactants, higherpressures and lower temperatures favour higher syngas conversion.

Methanol synthesis, which uses H2-rich syngas, yields a crude methanol product with 4 %to 20 % water by weight. If a CO-rich syngas would be used the product would containless water. As a result, raw methanol would be suitable for many applications at asubstantial savings in purification costs. However, methanol production reactions areexothermically limited; both above reactions are highly exothermic.

For syngas with a high carbon monoxide content, conversion is limited by hydrogenavailability. If a higher conversion is desired than the hydrogen content of the syngas

permits, one option is to utilize the inherent shift conversion activity of the methanolcatalyst. This is done by adding steam to the reactor feed. The steam reacts with some ofthe carbon monoxide to form additional hydrogen as shown below:

The hydrogen thus produced reacts with carbon monoxide to form additional methanol.

The extent of this reaction is equilibrium limited, and if syngas conversion in excess of 50% is required, then a carbon dioxide removal unit can be used in conjunction with steamaddition.

It is well known that the presence of CO2has a positive effect on the methanol formation

of the copper/zinc oxide catalyzed reactions. Approximately 6 volume % CO2is normallyadded to the syngas feed. [2] In the CHRISGAS project the CO2concentration in the gas


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phase accounts to about 1 volume %. [3] CO2 conditions and prevents damage to thecatalyst. Some studies have indicated that essentially all of the methanol is producedfrom the reaction of CO2 with hydrogen. [4] An internal water gas shift between the

resulting water and CO generates more CO2 for methanol production. The followingreaction schemes show the proposed reaction mechanism.

1.3 Industrial methanol catalystsIn 1923, scientists at Badische Anilin & Soda-Fabrik AG (BASF), Germany, developed amethod to convert synthesis gas into methanol. This process used a zinc chromatecatalyst, and required extremely vigorous conditions, such as pressures ranging from 30- 100 MPa, and temperatures of about 400 C. This catalyst was used in the high

pressure methanol synthesis up to the mid 1960s.

Modern methanol production has been made more efficient through use of catalysts(commonly copper) capable of operating at lower pressures. Today, the most widely used

catalyst is a mixture of copper, zinc oxide, and aluminaoxide first used by The Imperial

Chemical Industries (ICI) in 1966. At 5 - 10 MPa and 250 C, it can catalyze theproduction of methanol from carbon monoxide and hydrogen with high selectivity. Thereaction is carried out in the gas phase in a fixed bed reactor. The good catalyst life andselectivity, larger capacity single-train convertor designs, power requirements, andimproved reliability of the low pressure technology result in lower energy consumptionand economy of scale. Current catalysts may contain, next to copper and zinc oxide on

alumina, other stabilisers and promoters, such as alkaline earth oxides. These haveseveral roles, including inhibition of sintering, and poison traps that prevent poisoning ofthe active metal surface. In Figure 1.3 physical and chemical properties for a typical

methanol synthesis catalyst produced by Haldor Topse are shown. [5]

Figure 1.3: Physical and chemical properties for a methanol synthesis catalyst.

The active catalyst for methanol production is metallic copper. It is therefore desirable toreduce the catalyst before use, for example by passing hydrogen gas through the reactorin absence of the other components of the reaction system at 200 to 300 C. Preferably

the molar ratio Cu/Zn is 1 or greater than 1, e.g., to 10 and the Al content is 10 or less


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mole %. Zinc oxide helps in the formation of high copper metal surface area, slowsagglomeration of the copper particles, traps Cu poisons and reacts with alumina to inhibitdimethyl ether formation.

1.4 Methanol reactor typesAs said before formation of methanol is exothermic. Removing the heat of reaction while

maintaining precise temperature control to achieve optimum catalyst life and reactionrate is one of the most difficult design problems of methanol synthesis. Thus in aconventional fixed bed reactor design, heat control and removal is of prime importance.Several types of reactors have been developed to deal with this problem. Only a brief

summary of the reactors involved in MeOH will be given as they are subject of the reportconcerning MeOH reaction/distillation and DME production.

Catalyst beds or particles can be cooled directly or indirectly. Heat removal in fixed bedreactors can be facilitated by injection of cold gas in an adiabatic multibed quenchreactor, or by heating another medium such as water in a tubular cooled reactor. [11]These beds may give rise to hotspots when heat removal is not sufficient resulting incatalyst damage. A novel type of MeOH reactor that still is in its demo phase is a slurry

three phase bubble column methanol reactor (SBCR) used to process CO-rich syngasoriginating from coal. In this reactor an inert mineral oil is used to remove the reactionheat. The process (LPMEOH) is developed by Eastman Chemical Company and Air

Products and Chemicals, Inc. and is located at Eastman Chemical Companys chemicals-from-coal complex at Kingsport, Tennessee. [6]

Schematic drawings of the different used industrial MeOH reactors are shown in Figure1.4.

Figure 1.4: Schematic drawing of the industrially applied different methanol reactors: 1)an adiabatic multibed quench reactor, 2) a tubular cooled reactor, and 3) a slurry threephase bubble column reactor.


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2 Potential methanol catalyst poisons

Biomass is often referred to as a clean feedstock, most accurately pertaining to wood,which is low in mineral content; contains almost no sulphur or nitrogen; and is composedprimarily of carbon, hydrogen, and oxygen. However, other potential biomass feedstocks

are more problematic. Bark has more mineral, sulphur, and nitrogen, and leaves andtwigs (juvenile wood) even more so. Herbaceous biomass, such as switch grass, hassignificant levels of mineral content, as much as 10 - 15 wt%, and a relatively highnitrogen (2 - 4%) content as well as sulphur. Aquatic biomasses, such as kelp or algae,

have particularly high mineral contents, especially the marine species. Finally, wastebiomass often can contain higher levels of minerals (concentrated in the residue afterdegradation of the organic portions) and be further contaminated with soil.

Biomass as it may incorporate compounds in high concentrations such as nitrogen andmetal compounds compared to fossil fuels may cause problems to downstream hydrogenequipment. Deactivation of different upgrading catalysts is caused by poisoning,

generally from traces of chloride and sulphur compounds in the feed. Other types ofcatalyst poisons include phosphorus, silicon and unsaturated hydrocarbons. Also othertypes of deactivation occur such as sintering from the hydrothermal environment of the

reaction.

In this chapter possible methanol catalyst poisons and their effect on reaction kineticsand selectivity will be discussed. These compounds may occur from the biomass feed orthe reactor equipment and are introduced with the gas stream to the methanol synthesisreactor. Although an acid gas removal unit (AGR) will be installed that may remove mostcontaminants some may still slip through. For example, the sulphur content of the feedgas to the methanol synthesis plant after the AGR may be as high as 10 ppm. [3] In

Figure 2.1 elemental concentrations of possible contaminants in the gas phase after thegasifier as function of feedstock are listed. [7]

Figure 2.1: Element concentrations in the biomasses and estimated concentrations in the

flue gas, if elements are released exclusively. Cursive values are below the detectionlimit.

Several compounds containing the above elements have been identified as possiblemethanol catalyst poisons. These will be discussed here. Poisonous effects were studied

in gas phase fixed bed and bubble slurry column (SBCR) reactors, respectively, however,

results obtained for the liquid phase process are also applicable to the gas phase fixedbed MeOH synthesis process. [8]


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2.1 Sulphur compoundsSulphur compounds, such as hydrogen sulphide (H2S), carbon disulphide (CS2), carbonyl

sulphide (COS), and organo sulphur compounds (such as thiophene (C4H4S) and methylthiocyanate (CH3SCN)) have been identified as potential methanol catalyst poisons. [8]These compounds, and particularly H2S, form stable compounds on the catalyst surfaceand block its active sites. Initial reaction is most likely the hydrogenation of COS, CS2,

C4H4S, and CH3SCN catalyzed by the active copper metal surface. [9] H2S, the sulphurcontaining product, will then react with metallic copper to form CuS2. There appears tobe evidence that the copper poisoning by sulphur containing compounds in the presenceof H2 is reversible. The maximum allowable sulphur content of the synthesis gas fed tothe loop is 0.1 ppm v/v as H2S. [10,11] No reports were found describing the effects ofthiols, such as methanethiol (CH3SH), but based on the results for other sulphurcontaining compounds, these species are likely to be potent catalyst poisons.

In Fig 2.2 the effect of carbonyl sulphide on the synthesis rate of methanol is shown.[12] It should be noted that the graph was made for CO rich synthesis gas compared tothe synthesis gas from Vrnamo, indicating that the effect of COS on methanol catalysts

using hydrogen rich syngas may be different.

Figure 2.2: Effect of admission of carbonyl sulphide (COS) on the production rate ofmethanol

As sulphur compounds have been shown to be potent copper poisons, in practice sulphurpoisoning appears to be less of a problem. The presence of zinc oxide on the methanolsynthesis catalyst namely acts as a sulphur absorber; ZnO reacts with H2S to formthermodynamically stable ZnS and H2O providing the catalyst with improved sulphur

resistance. The small crystallite size of ZnO, coming from the method of manufactureensures fast absorption. [10] Most well-formulated Cu/ZnO type catalysts can retain ahigh proportion of their activity in the presence of sulphur compounds. It was found that

Cu/ZnO/Al2O3methanol synthesis catalysts retain a high proportion of their activity evenwhen they have accumulated quite large amounts of sulphur. [10] With an average of2% sulphur, the methanol synthesis activity of a Cu/ZnO/Al2O3 catalyst wasapproximately 80% of the un-poisoned activity, and with an average of 12% sulphur

activity was approximately 25% of the un-poisoned activity. In contrast, a Cu/Al2O3catalyst was completely deactivated with only 0.2% sulphur in the catalyst, showing oneof the major beneficial effects of having ZnO in Cu-based catalysts. In Figure 2.3 aphotograph of a ZnO catalyst particle reacted and unreacted with H2S is shown.

Severity of catalyst deactivation in the presence of sulphur poisons decreases in thefollowing order [8]:

C4H4S > CH3SCN > CS2> COS


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Figure 2.3: Photograph of a zinc oxide layer. Clearly on the left side the zinc sulphide

layer formed by irreversible adsorption of H2S can be observed3.

2.2 Halogen compoundsChlorine in any form (free or combined) is a virulent poison and should be excludedcompletely from the process gas side of any equipment. It is essential that chlorinated

compounds are not introduced into the synthesis gas production section or synthesis loopas solvents or degreasing agents during the plant construction, pre-commissioning or

maintenance periods. Hydrogen chloride (HCl) reacts with the active copper producinglow melting copper chloride (CuCl) that quickly sinters, thus reducing the copper surfacearea and killing the catalyst completely. [10] Even traces of chloride markedlyaccelerated sintering. The presence of chlorine caused an immediate decrease in catalyticactivity which continued even after the HCl source has been removed.

The presence of HCl will result also in the formation of zinc chloride while releasingwater. The formation of zinc chloride will, however, effect the sulphur absorption capacityof the ZnO catalyst and thus the sulphur tolerance of the copper catalyst. [6] Anothermajor problem is the high mobility of the zinc chloride under reaction conditions, whichalso influences the thermal stability of the catalyst. [10] To avoid the formation of zincchloride, HCl guard beds, such as potassium carbonate on an activated alumina carrier,

should be installed upstream the zinc oxide sulphur absorption step. [13] Fromexperimental work it is clear that ZnO can give no protection to Cu catalysts against HClpoisoning. [10] Based on experimental evidence the limits on HCl content in the syngasfeed to avoid catalyst poisoning are of the order of 1 ppb. [10]

Other organic halogen compounds such as methyl chloride and methyl fluoride also affectthe rate of methanol formation. Concentrations of halogens as low as 2 ppm led toincreased deactivation. [8] However, methyl chloride was a much more active poison

compared to methyl fluoride. Initial reaction is most likely the hydrogenation of organichalogen compounds catalyzed by the active copper metal surface, resulting in copperchloride or copper fluoride. CuCl or CuF can be reduced to metallic copper and HCl,

indicating that halogen poisoning is reversible. To remove these halogen compounds theyneed to be hydrogenated upstream of the methanol synthesis reactor.

Severity of catalyst deactivation in the presence of halogen poisons decreases in the

following order [8]:

CH3Cl > CH3F

2.3 Nitrogen compoundsNitrogen compounds are common catalyst poisons. However, nitrogen containingcontaminants hydrogen cyanide (HCN), acetonitrile (CH3CN), and methylamine (CH3NH2)had no effect on catalyst activity. Amines and nitriles have very low affinity for activecopper species. HCN is expected to react with ZnO forming Zn(CN)2 species, howeverthis was not observed during MeOH synthesis. The surprising inactivity of HCN is likely

3Courtesy of Engelhard Corporation, USA.


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attributable to its hydrogenation under methanol synthesis conditions to methyl amine,which was shown to have little affinity for copper. [8]

2.4 Phosphorus compoundsPhosphorus compounds, such as (substituted) phosphines (PH3, PR3) may function ascopper poisons. Phosphines can be formed by hydrogenation of phosphorous during

gasification. Poisoning by phosphine likely occurs by a reaction analogous to thatproposed for arsine. Concentrations of phosphine as low as 2 ppm led to increaseddeactivation. Analysis of spent catalyst showed a very low BET surface area.

2.5 Metallic compoundsThe catalyst is poisoned by metals (heavy metals or alkali metals) and arseniccompounds.

Precautions should be taken to minimise iron carbonyl (Fe(CO)5) or nickel carbonyl(Ni(CO)4) formation by thorough descaling of the equipment and pipework in theoptimum temperature region for carbonyl formation, i.e. in all hot parts of the loop. Iron

carbonyl can form when syngas is in contact with carbon steel (rust) while Ni(CO)4

results from contact with 304 and 316 stainless steel. An optimum temperature for metalcarbonyl formation is about 200 C. Both carbonyl compounds are generally found in

syngas, particularly those rich in CO.

Iron and nickel carbonyls will decompose on the catalyst, as they are thermodynamicallyunstable at methanol synthesis reaction temperatures. This will deposit a thin film of

highly reactive iron or nickel onto the surface of the catalyst. Apart from acting as acatalyst poison by restricting access to the active copper surface resulting in a dramaticloss of activity, this highly active species will increase the rate of certain by-productreactions (Fischer Tropsch) and will catalyse the highly exothermic methanation reaction.If this is believed to have occurred, even stricter limits should be imposed on themaximum operating temperature of the catalyst in order to prevent excessive

methanation and hence excessive temperature rise over the catalyst bed. Methanationover iron and nickel occurs at temperatures of 250 C. Fig 2.4 shows the effect oftransition metal carbonyls on the synthesis rate of methanol. [12] Note that although thegraphs were made for CO rich synthesis gas compared to the synthesis gas fromVrnamo giving rise to higher concentrations of gaseous carbonyl compounds the effectis unambiguous. After the addition of iron carbonyl was begun, the rate of catalystdeactivation increased by about 50%. In the case of nickel carbonyl addition to the feeda substantial increase in the rate of catalyst deactivation, roughly a factor of four,

occurred.

Figure 2.4: Effect of admission of iron (a) and nickel (b) carbonyls on the production rateof methanol

(a) (b)


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Arsenic-containing species, such as arsine (see Fig. 2.5), have been found in syngas feedto MeOH synthesis plants originating from coal. They were not mentioned in the studyperformed by Porbatzki and Mller. [7] However, there are indications that biomass also

contain arsenic compounds as natural constituents and often at remarkably highconcentrations (> 100 mg As per kg wet mass). [14]

Figure 2.5: Molecular structure of arsine

Catalytic testing in the presence of arsine showed that arsine was a powerful methanol

synthesis catalyst poison. [15] Arsine, at levels as low as 150 ppbv, resulted in a rapiddeactivation of the catalyst. Removal of arsine resulted in a deactivation rate consistent

with a clean synthesis gas feed; that is, arsine poisoning stopped when it was removedfrom the feed. Measurements of arsenic-containing spent catalyst indicated the presence

of zero-valent arsenic in an intermetallic surface phase that is structurally related toDomeykite (Cu3As). This indicates that arsine absorbed and dissociated on the coppersurface to form gaseous H2and Cu3As. Arsine thus reacts irreversibly with the catalyst

under the methanol synthesis conditions.

In Figure 2.6 the deactivation rate of the methanol synthesis catalyst as function of thearsine concentration in the syngas feed is shown.

Figure 2.6: Deactivation rate as function of the concentration of AsH3in the syngas feed.

Severity of catalyst deactivation in the presence of metallic poisons decreases in the

following order:

Ni(CO)4> Fe(CO)5> AsH3

Poisoning by alkali metals should be considered as alkaline impurities can result in theproduction of higher alcohols, and cause some decrease in activity, however, noliterature data has been found. Impurities of alkali may originate from the biomass feed,

catalyst or from carry over of solids from the boiler into the process steam system.

2.6 Steam

Steaming of the catalyst accelerates growth of the copper crystals and deactivates thecatalyst especially in the presence of chlorine containing compounds. Also it may cause


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particle breakage that could lead to high-pressure drop and non-homogeneousdistribution of flow through large catalyst beds and impaired performance. Therefore, thepresence of steam should be avoided.

2.7 Lubricating oilLubricating oil may originate from used compressors, and other moving parts within the

reactor unit. Oil in quantities greater than would be passed by currently designed glasswool filters is considered to have a deactivating effect on the catalyst, as it may blocksome of the smaller pores. [11] This may also result from in-situproduction of paraffinsby transition metal deposits (Fischer Tropsch) or acidic impurities.

Carbon deposition (coking)on commercial copper catalysts, is uncommon, as they areconsidered not to be acidic and as they operate under mild conditions. [10]

2.8 Industrial removal of poisons from syngas feedTest results for the LPMEOHTMprocess has indicated that the poisons identified in syngascan be removed from the syngas feed stream. These materials are documented in Ref.

[16]. The results of adsorbent screening have led to a conceptual low temperature design

for poison removal by adsorption. The first adsorbent bed would contain spent methanolcatalyst to adsorb H2S and HCl in a throw-away system. The next bed would contain H-Y

zeolite for Fe(CO)5 removal, followed by active carbon for Ni(CO)4 removal, and finallycopper oxide/chromium oxide loaded carbon for COS removal. The sections containingzeolite, and active carbon absorbents are thermally regenerable at 260 C. All adsorbentmaterials investigated are commercially available and the process cycle is eitherconventional temperature swing adsorption (TSA) or throw-away.

In the Vrnamo plant which forms the heart of the CHRISGAS project prior to the watergas shift (WGS) reactor most contaminants may already have been removed, althoughthe proposed sour gas shift catalyst is stable in sulphur containing syngas. Downstreamof the WGS reactor an acid gas removal unit is placed for the removal of CO2. This unit

based on a water-wash design may also be effective for the removal of acidic sulphur,halogen, and nitrogen compounds and alkali compounds. Only precaution needs to betaken into account concerning the formation of metal carbonyls.

2.9 ConclusionsPossible methanol catalyst poisons present in the syngas feed to the methanol synthesisreactor include sulphur, halogen, phosphorous containing compounds from biomass oriron and nickel carbonyls form reactor equipment. Poisoning by these compounds result

in site blocking or sintering, which yields decreased activity or change in selectivity.

Based on the results of several studies, the following ranking of methanol synthesiscatalyst poison strength could be obtained [9]:

Nickel carbonyl (Ni(CO)4) > iron carbonyl (Fe(CO)5) > thiophene (C4H4S) arsine (AsH3)

> methyl chloride (CH3Cl) > methyl thiocyanate (CH3SCN) > carbon disulfide (CS2) >carbonyl sulfide (COS) > phosphine (PH3) > methyl fluoride (CH3F).

Catalyst guard beds need to be installed for removal of these compounds. Severalmaximum exposure levels of poisoning compounds to methanol catalyst synthesiscatalysts are listed in Table 2.1 together with options for poison removal.


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Table 2.1: Apparent maximum poison concentrations for methanol synthesis catalyst andremoval technology

Poison Apparent maximum allowable

concentration

Technology

Sulphur as H2S 0.1 ppm ZnO guard bed;

spent methanol catalystChlorine as HCl 1 ppb base promoted alumina;

spent methanol catalyst

Phosphorous as PH3 < 2 ppm copper impregnated carbon

Metal carbonylsFe(CO)5

Ni(CO)4AsH3

< 1 ppm

< 1 ppm150 ppb

H-Y zeolite

active carboncopper impregnated carbon


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3 Further recommendations

In Chapter 2 several possible catalyst poisons have been identified. However, thesepoisons may originate from the feed, such as natural gas or coal. Therefore it may bepossible that the list in Chapter 2 is not complete.

It is therefore our recommendation to visit Sekundrrohstoff-VerwertungszentrumSchwarze Pumpe in Germany where they produce methanol from syngas produced frombiological waste mixed with coal in different types of gasifiers [17].

Some items of discussion may be:

1) type of catalyst, reactor type and conditions;

2) catalyst poisons affiliated to biomass not present in coal and their respectiveconcentrations, and;

3) installed gas treatment units before methanol synthesis reactor.


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Glossary

Abbreviation

AGR acid gas removal unit

CHRISGAS Clean Hydrogen-rich Synthesis Gas

CO carbon monoxideCO2 carbon dioxide

Fob free on board

H2 hydrogen

MeOH methanol

SBCR slurry bubble column reactor

Syngas synthesis gas: mixture of hydrogen and carbon monoxide

WGS water gas shift


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References

1. Chemical Business Focus Methanol, Tecnon OrbiChem, Nr. 301, March 19 2007.

2. Tierney, J.W.; Wender, I. U.S. Pat. 5,384,335, 1995, assigned to University of Pittsburgh, USA.3. CHRISGAS Internal communication; L. Waldheim, TPS Termiska Processer AB, doc.nr.: G119-02aTS006a.

4. Chinchen, G.C.; Mansfield, K.; Spencer, M.S. Chemtech, 1990, 20, 692-699

5. Methanol synthesis catalyst MK-121, Product sheet. Haldor Topse.

www.topsoe.com

6. Commercial-Scale Demonstration of the Liquid Phase Methanol (LPMEOHTM) Process, Clean Coal

Technology, Topical report number 11, April 1999.7. Porbatzki, D.; Mller M. Preliminary Report on Gas Contaminants from Fuel Bound Sources;

Forschungszentrum Jlich, Germany. CHRISGAS Deliverable number D78.

8. Quinn, R.; Dahl, T.A.; Toseland B.A.Appl. Catal. A: General, 2004, 272, 61-68.

9.Removal of trace contaminants from coal-derived synthesis gas; Topical report. Air Products and Chemicals,

Inc. & Eastman Chemical Company, 2003

10. Twigg, M.V.; Spencer, M.S.Appl. Catal. A: General, 2001, 212, 161-174.11. Methanol Plant Technology; Synetix Low Pressure Methanol (LPM) Process, Product sheet. Synetix

www.synetix.com

12. Roberts, G.W.; Brown, D.M.; Hsiung, T.H.; Lewnard, J.J.. Chem. Eng. Sci., 1990, 45, 2713-2720.

13. Chloride guard bed HTG-1, Product sheet. Haldor Topse.

www.topsoe.com

14. Francesconi, K.A.Environment. Chem., 2005, 2, 141145.

15. Quinn, R.; Mebrahtu, T.; Dahl, T.A.; Lucrezi, F.A.; Toseland B.A. Appl. Catal. A: General, 2004, 264,

103-109.

16. Liquid phase methanol LaPorte Process development unit: Research and Engineering support studies;

Topical report Task 3.4: Adsorbent evaluation for removal of catalyst poisons from synthesis gas. Air

Products, 1990.

17. Bandi, A,; Specht, M. Gewinnung von Methanol aus Biomasse, Zentrum fr Sonnenenergie- und

Wasserstoff-Forschung, Baden-Wrttemberg, 2004.

methanol catalyst poisons - a literature study (ccs)

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