2,666,690 Jan. 19, 1954 |-|_ o. FOLKINS ErAL PRocEss FOR THE PRODUCTION 0F CARBON DxsuLFIDE

2 Sheets-Sheet 1 Filed DeCS.y 28, 1951

H. o. FoLKlNs ETAL 2,666,690 PROCESS FoR THE PRODUCTION oF CARBON DISULFIDE

2 sheets-sheet 2

|| _ ww _ t l

Jan. 19, 1954

` Filed nec. 28, 1951

Patented Jan. 19, 1954 2,666,696

f UNITED STATES PATENT] OFFICE . ' ' PnooEssFoR THE PRODUCTION oF

v CARBON DISULFIDE

Hillis 0. Folkins and Elmer Miller, Crystal Lake, and Harvey Hennig, Cary, Ill., assignors to Food Machinery and Chemical Corporation, New York, N. Y., a- corporation of Delaware.

ApplicationvDecember 28, 195.1, Serial No. .263,724- 18 Claims.

1 . The present invention is directed to a process

for converting hydrocarbons to carbon disulfide yby reaction with sulfurv wherein a scavenging or agglomerating material is utilized to nulliiy the deleterious eiect of side reaction products.

It is known to prepare carbon disulfide by reaction of sulfur with various hydrocarbons un der catalytic 'conditions 'at elevated tempera tures and pressures. It is reported that hydro carbons having one to three carbon atoms in the molecule 'are preferred for the reaction for economic reasons, although certain investigators show that unsaturated hydrocarbons and higher molecular weightr hydrocarbons may be satis factorily used in the process. Because oi the complexity-of the reaction when using higher molecular weight hydrocarbon charge gases wherein there are produced various side reaction products, it is generally preferable to use meth Iane or a gas comprising highV percentages of methane for the reaction. Experiments have in .dicated that _hydrocarbons containing two to Iive carbon atoms in the molecule are prone to yield deleterious side reaction products which contaminate the carbon disulfide product; cause severe catalyst decline and consequent vdrop in conversion, and contaminate the recycle sulfur, making its recovery for reuse more difiicult. -T-he ynatural gases containing 4 mole per cent ofrCs hydrocarbons and 1 mole per cent or more of C4 ' hydrocarbons have been designated as border line charge gases for the carbon disulfide reac tion since even these small amounts of- hydro carbons of higher molecular weight than methane have beenrfound to cause Vsevere catalyst con- .-. tamination and plugging of the reaction zone with tars and polymers. ' _

p lNumerousl techniques have been developed for increasing the eiiciency of the reaction and the ease -' of product recovery. These include new catalysts, use of an excess of _sulfur over the stoichiometric requirements, preheating the

charge gas and' sulfur to reaction temperature orabove, and techniques for separating the car-_ bon disulfide from the` excess sulfur and side reaction products. These improved techniques have greatly increased the amount of carbon di sulfide which can bev obtained from a given amount Yof charge gas;UA However, in their prac tice it is not always i possible to conduct the

(Cl. 23-206)

15

45

5

2 n. , .

reaction under conditions that are kinetically optimum for each hydrocarbon gas. For exam ple, in some instances the space velocities of the reactants through the reaction zone must be ad justed downward from optimum space velocities suitable for the particular reaction environment of hydrocarbon gas and operating conditions used, in order to obtain maximum yields per pass from the reactants. The alternates to lower space velocities are to increase temperature and hence corrosion diiiiculties or to operate' under high pressures. Generally, the use of higher space velocities lowers the extent of conversion. Too low a conversion level will interfere with product separation and recovery. By operating under conditions of lower space velocities, higher conversions to carbon disulfide may be main tained, but the process is more inefficient and productivity may be lower. Naturally, the use of excessive amounts of sulfur complicates the product purification steps and sulfur recovery. The present process eliminates the above prob

lems without sacrifice of any of thev advantages gained from the use of theabove mentioned techniques, and is based on the discovery that by removing the deleterious side reaction prod ucts as they are formed by use of an agglomerat ing materialpresent during the reaction, their eiiect upon the reaction is minimized and the sulfur content thereof is made recoverable. Re moval of the side reaction products allows oper ation at. all times. under optimum reaction con ditions for maximum yield per pass without com plicating product recovery or sulfur recycle.` This

- is extremely advantageous in a reaction of this type wherethedeleterious effects of the sulfur containing sidereaction productsfincrease with time and the presence ,of even a small amount in the reaction zone is very detrimental.

Accordingly, it is the primary object of this invention to provide a process for producing carbon disulde by reaction of hydrocarbons with sulfur under conditions of maximum convert sion, with a minimum of influence from side reaction products and with little or no diiiiculty in product recovery or sulfur recycle. A secondary object of` this invention is to pro

vide a .process for the eiiicient> and economic production of carbon -disulfide from hydrocar bons that are prone to form vdeleterious sulfur

.have proved eiective.

.struction include :aluminum coated steels, ire

.Iractory linings, -and .other .types of :stainless steels. l

2,666,690 3

containing side reaction products wherein an agglomerating material, which may be catalytic or not, acts to remove these deleterious side re action products from contact with the reactants before there has been an opportunity for them to lower the reaction emciency. Another object of this invention is to take

advantage of the unreacted sulfur content and the combined sulfur content within the effluent products, removed by the agglomerating material, to react 'with aprincipal byeproduct, hydrogen sulfide, .from `the reaction, thus 'reforming in usable condition sulfur which would .otherwise be lost.

Still another object of this inventionis topro vide a process for producing carbon `disulfide wherein an agglomerating material removes the tars, polymers, some of the excesssulfur, anilsul fur-carbon complexes for exidationito substan- ` tial amounts of sulfur dioxide, Whiehis'utilized" to react with. the hydrogen suld'e'byeproductito form elemental sulfur for reuserinrthe ...reaction Further objects and advantages of the inven

tion will become apparent as the description thereof proceeds. The term principalproducts fas =used'herein

appliesto the carbon disuliide andhydrogen sul-' fide which are ` the normal Yproducts Ao thevco'rr. plete reaction rof sulfur >and -charge gas. "The term sidereaction.products'wil1lbe usedto refer to Vthe Aproducts formed from Vthe~'incomplete sul fur oxidation >of fthe carbon andhydrogen-con tent of the charge -gas. These "include carbon 'hydrogen-sulfur complexes, 'sulfur-carbon com plexes, tars, and coke 'above referred to. . In the accompanyingdrawingsjFigure"l shows

'one'typeofreactor for producing carbon disulde and a -system for loxidizing' thehydrogen sulii'de to elemental sulfur. `l'iefure'Zshovvs a'system'for separating carbon disul?ldefromhydrogen sulfide and othersid e reaction products. The present-process lis best described "byrefer

ence vtothe accompanying drawings. In Figure ~1 the charge gas is 'introduced'at vline v,fcontrolled by valve fdfinto coil S of'heatertavhereiit ispre heated >to reaction "temperature `or above. Ele mental suliur is introducedromsulfur hopper I0 into sulfur melter ZWhere itis meltedlby steam `in coil lll. Heat is appliedto coil ift-so that the `moltensu'lfur is kept at atemperature between approximately 250 'fand 300 F. and preferably about 270 Obviously, those temperatures lare to be avoided at which~viscoussulfurforms. The 4molten sulfur is pumped from the melter Vi2 by means of sub-merged centrifugalpump VT5, lsuit- " `able forhandling molten'sulfunthrough'lines f'l' `and 2U into coil 22 Aoi" heater 8. lSufficient pres sure must 'be used >to force the Vmolten, sulfur 'through coil 22. For this Upurpose, pressures "up to 100 pounds per square-inch-ma-y be used. The ypressures 4under 'which the >molten sulfuris moved throughout the system will Idepend ` upon `'the 'op eration pressuremaintainedin the reactor, Tur naces, and converters. That portion of the equipment Whichis > in 'con

-tact -With sulfur-bearingvapors at elevatecl"tern- vperatures >is ` cest constructed vof - a >materialwhich -is 'resistant "to the corrosive -action lof sulfur. Various stainless 'steel alloys, such as those -ofl high `chromium content, Vand 4cliromiuzneniclcel stainless steels stabilized ywith molybdenum, etc.

Other -materials 'of con

20

30

4 In coil 22 of heater t, the molten sulfur is

heated to a sufficiently high temperature to vap orize it, as for example, 850 to 12%o F. under given operating pressures. Preheated charge gas leaves coil S by line 24, controlled by valve 25, and passes to line 225 Where it joins and uidizes the agglomerating or catalytic material before enter ing reactor 3E). Sulfur vapors proceed from coil 22 via line 32, controlled by valve 34, to join the charge gas before it enters line 28. Simultaneous intro'ductionef ythe reactants finto .Contact with "each other and "into contact with the agglomer ating material bei-ore their entrance into the re -'actor is generally the preferred technique. How -even ins-ome cases, especially where higher hy -idrocarbons are being used as the charge stock, it maybe preferable to introduce the sulfur vapor y'.to'f.theireac'tor separately. In this case, the sulfur vapors pass 41Vfrom line 32 to line St, controlled by ~valve38,.intoreactor 3&3 where they meet the hy 'drocarbonggas and "fluidized material. Both the 4icuteheatecl rchar-.ge :gas and the vapor-ized sulfur may be subjected to superheating to reaction tem peratures or above prior to their entry into re.

" actor 30. 'Reactor 3B >is providedmvith a bottom conical

shaped section it!) yirivvhich the Ya'dmixture.sofipre heated sulfur vapors vand:chargefgas takes'place. A vertical return .sta'ndpipe'iz lprovided with-.valve 44 for controlling the flow of iluidized :mixture therein is located vwithin Lthe centralportion of reactor '30. Standpipe i 2 extends `from lower conical section F493 yto upper enlarged conical sec tion 46. Make-up agglomerating 'material is

' introducedinto'thesystem iromhopper fgcou trolledby valve 5.5,into line T23 whichf'eeds *di rectly into'lower conical'secti'on 13D >oi reactorll

' via line 52, controlled"by1valve`54~ fUnderfeertain

70

conditions, itV maybe desirable to vutilize'tlfle latent heat content of the regenerated agglomerating material to aid in the lvaporization and 'super heating ofthe sulfur; "forthis purpose, the'fhvdro carbon chargegasheated orunhe'ate'd, passes via lines 24 or 56 into line 28 Where'iluidiza'tion o'f the agglomerating material-takes place. The iiuid~ ized mixture passes 'from line 28 fv'ia fline "58 'and valve 60 to ` jo'infthesulfur stream at a point in coil >22 where :the 'temperature 'iis 'about Athe boil ing point 'of sulfur. The heated lmixture leaves

. Acoil 22 and entersreactor 30 ` via lines 32 fand F35. 'Contact of the -agglorneratingfmaterial with the reactants takes place in'reactor Si@ in the same manner as is employedin'the'moving bed, >pebio'le and v'llhermofor cracking processes, Standpipe 42 serves'to vcontrol the'llow of heavier-particles -through the iiuidized mass. Conical section '46 is designed 'so that the maximumhindered settling takes place therein.

Accordingly, reaction vproducts and Athe fine portion or smallerparticles of ,agglomeratingfma terial rise to the-small upper >section 62Sfor pas sage into .cyclone separator 264.. `Cyclone .separa tor 6.4 .serves to .separate .the line particles -of agglomerating material rom the reactionprod ucts and return them into zthe denser-phase .of the reaction. Reaction products leave the'top vof reactor 3G vialineii to )pass 4:to the carbon disul >nde-hydrogen suldefseparation vsystem yto .be kde scribed in Figure 5.2. The vreaction products may contain considerable amounts 4ofinesulfur par ticles -and isome naggloinerating material. This A-inay be removed .(in apparatus notshown) by subjecting the product :stream Vto .countercurrent

contact 'with cold :Waterfollowed by 'mechanical

2,666,690

separation of the sulfur and agglomerating mai terial, which is returned to regenerator 68.

Heavier particles of agglomerating material leave the reactor 30 by line 10, controlled by valve 12, to enter the bottom of regenerator 08. 'Regen erator E3 may be an ordinary furnace type re# generator for oxidizing theI agglomerating mate rialtoiree it 'fromocclude'd tars, polymersrand sulfur-containing productsf The principalfprod ucts of this oxidation'willb'e sulfur dioxide, car bon dioxide, carbon monoxide, and water. yRe generator 68, as shownin Figure l, is a fluid type

' regenerator whereinvthe- oxidizing gas isY intro duced at line 1d. Burning .of vthe agglomerating

' material takes place throughout the central por tion of regenerator 68, andthe regenerated ma terial is caught in the annular space defined >by inner cylinder I6 and the outer wall of the. re-`A generator for return via! lines 'I8 and 28 ` to the reactor 30. The cycle of agglomeratingmaterial from- the reactor into the regenerator and back into the reactor is continuous and conditions are maintained for complete ~fluidization throughout the system. ' i f y

' Gaseous oxidation'products' from- regenerator 68 pass through line 80', controlled by valve 82, to catalytic converter 84 for the next step in the operation comprising the recovery of sulfur there from. On 'a molar'basis, for each mole of hy drocarbon gas reacting with four moles of sulfur, there are produced one mole of carbon disulfide anl two moles of hydrogen sulfide. One mole of sulfur dioxide will be required to convert the two moles of hydrogen sulfide tofree sulfur. Since from the carbon disulfide reaction there will be produced in the form of tars and polymers ad -mixed with unreactedlsulfur, an amount up to about 0.5 mole of sulfur, in combined and uncom-l bined form, which will yield an equivalent num ber of moles of sulfur dioxide in the regenerator, there will ybe an excessof hydrogen sulfide to be oxidized by the sulfur dioxide. Consequently, a portion of the hydrogen sulfide ranging from one tenth to one-third is oxidized to form addi tional sulfur dioxide Vforthe reaction. For. this purpose, hydrogen sulfide from the separation system (described in Figure 2) is conducted through line 88, controlled: by valve. 88, toY fure nace 90 wherein it is` oxidized to sulfur' diox ide. exothermic, and advantage is taken offthisto preheat the incoming hydrogen sulde and air within the furnace itself. Furnace 90 may be packed with high temperature fire brick. Pre heating the entire furnace by burning natural gas therein may be necessary in; order to bring it to operating temperature before the reactants -are introduced. By-pass line92 is Vprovided to con-. duct the balance of hydrogen sulfide .to the cata

` lytic converter 84. The mixture of sulfur diox ide and water formed in furnace 00 is conveyed by line 94 to waste heat boiler 85 wherein they are cooled before passage to catalytic converter 84 by line 98, controlled by valve |08. ` kThe final step in the sulfur recovery comprises

complete reaction of the sulfur Ydioxide content from theregenerator 68 and furnace 90A with the balance of hydrogen sulde to form elemental sulfur. This is accomplished by means of cata lytic converter -84 where in the reactant gases pass downward through catalyst bed |02. The catalystfor this purpose may be coarse Porof4 cel, a-highfiron activated bauxite which is-sup'. ported onv a stainless steel screen r'estingon ~al cast; iron grate..y Normally vthe ,operating condie' '

The reaction taking place in furnace 90 is i

6 . tions within converter 84 are from 500 to 750 F. The reaction may be caused to take place in one or more stages. For example, the first stage may be maintained at about 750 F. vand the second stage at about 500 F. If necessary, heat maybe applied to the reactor in order to initiate the re action. The conditions Within converter 84 are subject to some variation as long as the complete- oxidation of the sulfur takes place.

vEffluent gaseous products from the converter are admitted at the bottom of sulfurv wash tower |04 by means of line I 05. Sulfur wash tower |04 is provided with a mistseparating section |08 and a suitable contact area I I0. Within the tower the gases are subjected to countercurrent contact with a stream of molten sulfur conveyed from sulfur melter I2 vialines I8, H2, and II4 through spray I I6. bottom of sulfur wash tower and any heat ab

' sorbed from the hot gases or from the con densation'of the sulfur vapor is removed byj in direct heat exchange through cooling coil II8.

t Pump |20 serves to recycle molten sulfur to spray

-60

Ti)

I I6 when sufiicient sulfur has accumulated in the bottom of tower I 04. When the process has reached this point, the recycling of sulfur through line II 2 may be discontinued. Excess sulfur is withdrawn through line |22 and passed to >`flash

~ drum |24. Flash drum |24 eliminates the'occu pational hazard in sulfur melter I2 due to ab sorbed hydrogen sulfide by flashing it off at at mospheric pressure. f The sulfur within flash drum |24 is returned to sulfur melter I2 by line |25. i Referring now to Figure 2, the carbon di

sulfide separation system, reaction products enter through line 280 into the lower portion of absorber 202. The absorber is fitted with Raschig rings or other liquid-gas contacting ele ments. Absorber 282 is preferably maintained at a pressure of approximately 20 to 50 pounds per square inch gauge in orderyto absorb carbon disulfide from the reaction product gases. >Lean oil is pumped into the top ofV the absorber from accumulator 204 through line 208 by means of pump 2id. As absorber oil, heptane, or petro leum naphtha having a boiling range of about 250 to 400 F. or other fraction boiling above the boiling point of carbon disulfide may be used. Other -solvents or absorbing mediums such as benzene and o-dichlorobenzene may be used. It is preferable to choose an absorber oil which has a boiling point or boiling range not too far 'above the boiling point of carbon disulfide in order to enable the latter to be readily stripped therefrom. However, heavier absorption oils may be used and stripping carried out with the aid of a stripping medium suchv as- steam, methane,- or other inert gas. The unabsorbed gasleaves the top of the absorber through line 2|2 and passes to furnace 98 and catalytic cone verter 84 of Figure l. This gas is composed of hydrogen sulfide with a small amount of hydro carbon gas and about 0.5 per cent'or less of car bon disulfide. The rich oil is withdrawn from the bottom of absorber 202 by means of pump 2I4, passed through steam heater 256 where the rich oil is preheated to a suitable temperature, as, for example, 208 to 350 F., and charged to the middle section of stripper 2i8. Stripper 2I8 is provided with Raschig rings 22d or other liquid gasV contact elements. Carbon disulfide is strippedfrom the absorber oil and passed- from> the top of the stripper through linef222, water cooler 'or condenser224, where the temperature

Molten sulfur accumulates inthe

. .boiler 25S.

2,363,690 7

is reduced to 31019112- 'or less, to accumulator 22.6. f'gas and/'or vapor which vremains "uncon

'densed sleeves, the. accumulator '225 through vline 223 yand is returned to the .inlet of the fahsorber 232 'through line v221B. The stripper 2 i3 prefer ably 'operated at a pressure slightly above the :pressure in 4the yabsorber .262, as, for example, 25 -to 55 pounds per square inch gauge', .in order to avoid the necessity :of compressing the Y.gas re turned ythrough -line 228. . i

.'Ifhe vabsorber -oil is Withdrawn .from ` the >plate 230 in 4.the bottomrportion of stripper 2i 8 through line i232 vand lcharged Ato reboiler v234 and thence returned throughline 235 to the section of the stripper below the plate 230. Plate 239 .is pro vided with V.vapor uptakes 238. Lean absorber oil is withdrawn from the bottom of stripper 2:28 through line `cooled in Watercooler 242 to :a temperature below 106 F., and returned ` to ac cumulator 2534. oil from absorber i2-ii?. can be used to ,partially cool the lean oil from stripper' il?, .by providing a suitableheat exchanger. Fresh absorber -liquid. is I'added to :accumulator 294 -as required .through line 2.44. ' Liquid carbon .disulfide is Withdrawn from ac

cumulator i226 through line 2th and charged lby means of pump 248 to stabilizer 25d. Aportion of .the'carbon disulde may be pumped >through , line .252 -to the upper portion of stripper 2i8 as redux. The stabilizer :25d is operated at pres sures of 20 pounds per square inch gauge or above,1and,preferably inthe ranges of 5) to -150 pounds. The temperature in the bottom of the stabilizer is that needed to eiiectivel-y boil the >carbon disulfide Iand >free it of >hydrogen .sulfide and hydrocarbon gas under the conditions of operation. The stabilizer 25B is equipped with contact surfaces 254, such as Raschig rings, with apla'te 253 having vapor uptakes 25B and a re

In the stabilizer 25d, any hydrogen sulfide or hydrocarbon gas absorbed in the car bon disulde is boiled off and passes overhead through line 2&2 through Water cooler 254. A small amount of carbon disulfide passes over head, is condensed in part in cooler 24,~and collected in accumulator 266. The condensate from accumulator kit@ is returned to the top oi the stabilizer through line 268 by meanssof pump 210. The uncondensed _gases and vapors are withdrawn from the accumulator 266 through line 212 and recycled to the inlet `oi .absorber >2il2 .through linell. The bottoms from the sta bilizer 25.0 are withdrawn through a pressure con trol valve 214 .and charged through line 216 with the necessaryheating or cooling, `to the middle portion >of fractionating column l2.78 from which the carbon disulhde is .taken overhead through line 28B, condensed _in water cooler 282 and col lected in accumulator k28A as ,iinished product. Any bottoms, such as absorption oil, which may have passed overhead with thefcarbon disulfide 'from stripper 228 are withdrawn from the bot tom o'f the fractionator 2i'8 through line 236. Fractionator 2li? is equipped with contact surn lfaces 238, such as Raschig rings, a separator plate 2.3i) having vapor uptakes 2&2 and a re boiler 2M. Fractionator 218 is preferably oper ated at atmospheric pressure. The finished >car bon disulfide is Withdrawn from the accumulator 284 by means of pump 28E through line 298 to storage. .A portion of the carbon disulfide may he .recirculated through line .3M as .reflux >to y.the topof the fractionation-278. _

-Having thusdescribed ` the apparatus useful in

it will he apparent that the rich ~>

-5

15

70

.175

carrying foutfthe invention, attention is now fdi rected to the reactants, thefgeneral reaction con ditions, :and .the techniques employed in both the thermal andcatalytic aspects Yof lthe invention, in addition to pointing-out ` speoiiic 'examples :of the DIOCBSS. ,

The chargegas of theipresent process will ` com prise .anymixture- of hydrocarbons which vcon tain :small amounts, that is, borderline amounts, of constituents which fare _prone to .form deleterious side reaction products, to larger amountsV of these. constituents. A typical hydro carbon comprises ya lnatural gas containing in excess of -one mo1e,;per cent of C4 and higher ' molecular weight 4hydrocarbons or jmore than four mole viper cent :of :C3 and higher molecular Weight hydrocarbons. AHeavier gases including propane, -butana :and :even unsaturated .higher molecular weight `hydrocarbons may be used. The agglomerati-ng material, as has been stated, may be >either'catalytic or Vnon-catalytic. If the material is non-catalytic, the >reaction is con ducted kunder substantially Ythermal conditions and the agglomerating material used may'com prise -sintered alumina, silica, fdiatomaceou-s earth, and pumice. >Suchxnaterialsshould have :a par ticlesizesuicientto pass through -a 100 `to .200 mesh 'screen in order that -they vmay -be vproperly ?luidized. If `a moving >bed process is used, -the pellets may measure from 1/8 inch to %;inch. `In conducting the thermal reaction, the zpurpose of the inert ` agglomeratingmaterial` is `to "fscavenge the tarry rand reaction or residencetimes -will vary .according to the tem perature .employedand .according to the type of hydrocarbon charge gas used. The preferred reaction times "are in .the order of 0.5 to '25 sec onds `under .atmospheric pressure conditions. When higher pressures yare used, vthe reaction times ` Will fbe v'relatively increased. Since unsat urated hydrocarbons react'more readily than sat urated hydrocarbons, with other factors being- equal, .the reaction time for the former will be lessened. l

4Semeral catalyticmaterialsare available which lwill serve .to both vpromote `the lreaction and, when used according to the methods outlined

2,666,690

here, will serve to remove deleterious side reac tion products. These materials include synthetic silica-alumina, silica gel, fullers earth, bauxite, activated alumina, and in general .thosetypes of clays Ywhich are effective in theiremoval of color bodies and gum-forming bodies from petroleum oils. These catalysts may be used alone- or in combination with one oivmore; compounds of metals of groups IV, V, VI, VII, and VIII of the periodic table -as promoters. The oxides of zir conium on silica gel or activated carbon are es pecially eiective catalysts. Oxides of titanium and thorium may likewise be used. In addition, the oxides and sulfides of iron, vanadium, chro mium, molybdenum, and manganese may be used as` >promoters in combinationv with silica gel, fullers earth, or activated alumina catalysts. When conducting these reactions catalytically,

lower temperatures maybe employed, the pre ferred range> being from 842. F. to 1300YF. For both Athe catalytic and thermal reactions, it is preferred to use about the stoichiometric amount of sulfur needed to react'with ` all of the carbon and hydrogen ofthe hydrocarbon to form car bon disulide andk hydrogen sulfide. Theratio of lsulfur to hydrocarbon charge gas may, how ever,vary considerably and it is preferred to op erate with an amount of sulfur between 10 per cent in excess Aof stoichiometric requirements and 110 per cent below stoichiometric requirements. Within this range, reactions leading to the forma tion of low boiling sulfur compounds such as mer captans and alkylsuldes are minimized and at the'same time the amountof recycle sulfur that would have to be regenerated with the tarry products is limited to avreasonable amount. Al though the-reaction has been described through the use of the iluidized technique, other methods may be used tov circulate the catalyst or ag glomerating material through the system.- VThese include movingbed methods such as those em

_ ployedin pebble heaters and in Thermofor crack ing processes. Another procedure 'consists in mixing the agglomerating material to~~form ar slurrywithfthe liquidsulfur to be charged to the reactor.- An alternateprocedure comprises fluidizing the agglomerating material with the sulfur vapors at apointafter vaporization and before orduring the super-heating of thesulfur. A preferred feature of> the thermal technique is to- separately preheatthe sulfuryapors and hydrocarbon charge gas up toreaction tempera tures and then combine these preheated streams immediatelyV prior to their entrance into ` thefre action zone, This procedure overcomes thel de' hydrogenating effect of hot sulfur yvon the hy drocarbons with subsequent coke formation. - Whether ` thermal or catalytic; the rreaction

conditionsand proportions of reactants may vary somewhat~depending~onthe type ` of charge gas employed. Based on reaction conditions of about 1112" F. and atmospheric pressures the weight ratio of agglomerating material to charge-gas may vary-from.- 1:1 -tof20:1 with thepreferred range -being 2:1to 10:1 and thermedian about 5:1. ' yThis may be based on either a 10 per cent deficiencyor 10 percent excess on stoichiometricity.Y

IIYhe regeneration-of used

of sulfur based

suspension> through a regeneration zone under conditions adapted to cause combustion of the occluded tars andpolymers .1 collected on the sur.- . facethereof. during >contact .Withthe reaction

agglomerating ma-- _ vterial is' eifected by suspension ofthe particles.

in an oxygen-containing gas and passage,V of the

15

20

3 0

40

50

10 mass. The temperature of the regeneration may be controlled by recycling into the regeneration zone a portion of the regenerated agglomerating material after this portion has been cooled toa suitable temperature in aV cooling zone extra neous of the regeneration zone. The quantity of cooled recycled agglomerating material is de pendent upon its temperature, and decreases with decrease in temperature of the cooled recycled material stream. Common practice is to with draw the cooling material stream from the dense phase of the mass Within the regeneration zone, cool it to the desired cooling temperature and recycle it -to the regeneration zone.

It is apparent from the description thus ffar that the method of operation of this invention permits the >continuous ecient conversion of higher molecular Weight hydrocarbons into car bon disulfide. By operating in accordance with the invention, these higher hydrocarbons are reacted almost quantitatively _to carbon disul fide with continued high catalyst activity throughout the reaction. This isV inherent in the process since the reactants are'- continually be ing contacted with fresh or regenerated agglom erating material under either thermal or cata lytic conditions andthe agglomerating material is continuously removing the deleterious side re-. action products from contact with the reactants> during their combination to .form carbon disul de and from the atmosphere of thexreaction. The sensible heat carried by the regenerated ag glcinerating material, when recycled back into the liquid sulfur stream, will aid in the Vapori zation of the sulfur 'and its subsequent super heating. The present method also provides an efficient means for the reclamation of the sulfur content of they tar or free sulfur admixed or in solution with the tar for recycling in the'proc' ess. Lastly, sensibleheat is provided >for the reaction itself under endothermic conditions of operation. ' ` f

` kThe following examples are given to illustrate the invention: ' _Example 1.-Substantially pure ethane- gas wasL

reactedv with, a stoichiometric amount of sulfur vapors at 1112c F. in a fixed bed reactor. Ini tiaily only a small amount oftar formation was experienced. However. after a few hours, con~ 4.version to carbondisulfide had declined from its initial level- of .90 per cent to a value in the order> of 20 per cent, and it was necessary to reactivate the catalyst. _, Example AfA natural gas containing 91 per

centmethane, v5 per cent ethane, 2 per cent pro pane,l 14 per cent of C4 hydrocarbons, 0.5 per cent

t of pentanes and >0.5 percent hexanes and heavier

60

75:

hydrocarbons was passed at substantially at-_ mospheric pressure intoa reaction zone Jmain ktained at a temperature of 1112 F. and fitted. with a static bed of silicagel catalyst. Employ ing a stoichiometric ratio of gasand sulfur at a total space velocity of 450 (gas and sulfur (S2) volume calculated at 0 and 760 millimeters of niercurw , a conversion _of 58 per cent ofthe hy drocarbon gas to carbon disulfide was obtained. It was found Aunder these. Iconditions that com peting side reactions occurred to such an extent Y that aboutA 2 per cent of the charged gas 're--y acted with the sulfur to yield a viscous tarry polymeric material .and some coke, With the re- ' sult that a material decrease in over-all >eiiiciency and catalytic activity followed. Recovered Vsul _fur .was around 40`per cent'of that charged.' An initial high conversion-'of around 76 per cent

acca-,69o ll

was attained fora period of about one hour after which conversion dropped gradually and after. about six hours operation, conversion leveled off at about 58 per cent. Example 3.-A natural gasv containing around

3.0 per cent of C4 hydrocarbons and heavier is passed through a uid reactor using the iluid technique in the presence of the. saine agglom erating material or catalyst as used in Example 2. The reactor. is maintained at 1112o F. under substantially atmospheric pressure conditions. rIvhe sulfur to gas ratio is controlled to approx imately stoichiometric requirements. The Weight ratio of catalyst. to natural gas is maintained at about 6:1, and the. contact. time is about ten seconds. The over-all conversion of the hydro carbon. gas over. a period of 12 hours will bev about. 90 per cent. of .which 88 per cent appears. as carbon disulde, and 2 per cent as tar. Ten per cent. of the natural gas remains. unreacted and 'substantially 10 per cent of the. sulfur is un reacted. From the. above examples, it isseen by em

ployingA the technique ofthe present _invention the. .deleterious eiect of side reaction products .

eliminated andtheoverali reaction efficiency is maintained. atv a high level. Although the inven tion has been described by specic embodiments, these. are only illustrative and the only limita tions. to be placed. on the. invention are found in the. appended claims.

. What is claimed 1. The method of converting hydrocarbons to

carbon disuliide by reaction Withzsuli'ur, said hy drocarbons.. `containing constituents tending to form tarry sulfur-containing. by-products, com prising passing preheated hydrocarbons and pre heated suliur vaporsv into contact With an ag glomerating material in a reaction zone, said ag glomerating. material being capable of occluding saidisulurecontaining by-products and-said reac tion zone being maintained under conditions to promote. the formation of , carbon disulfide and hydrogen sulde, separating said agglomerating material and. the` carbon disuliide and hydrogen sulfide so.` formed, subjecting' said agglomerating material to. an oxidizing atmosphere capable of oxidizing the sulfur contenter said occluded by products to. sulfur dioxide, and reacting said sul fur dioxide so. produced With- the hydrogen sul fide under conditionsV to produce elemental sul~- ur for reusein the reaction.

2. rihe method in accordance withy cla-im 1 inl which the aggl'omerating` material is selected fromy the. group consisting of sintered alumina,Y silica, diatomaceousr earth, silica gel, activated alumina, vactivated clays,- andsilica-alum-ina coin' positionsi. _ `

3. _The. method in. accordance with claim 1- inf whichl the hydrocarbon isselected from- the group consisting of natural. gas, propane, butane, and their existing olenie homologues and mixtures thereof. - = ' Y

`4. rThe method in> -accordance with' claim 1 in Which the. carbonv disulfide forming reaction isv . conducted ata temperature between about 842 Rand 1500 F., and the ratio of agglomeratingy material: to hydrocarbons. is in the range'of 2:1 to10:1.A ` - Y'

_5. `'Ihe method in accordance with claim 1 in Which the hydrocarbons. andsulfur are preheated` to reaction temperature._

6. _The method in accordance With claim 1v in. Which the sulfur is present in an amount betweenA a4 I0 per cent deficiency anda 10 per cent excess

il

20

40

75

l2 of. stoichiometric requirements. for the reaction;`

7. The method in accordance with claim, 1> in which the oxidation of occluded sulfur-contain ing by-products on said agglomeratirig material

Vis conducted at temperatures in the order. of 800 F. to 1500L7 F.

8. The method in accordance'with claim 1. in which the reactants and agglomerating material aremaintained in a I'luldized state Within the re action zoneat about 1112 F; under s'ubstantlally; atmospheric pressure with the ratio or' agglom erating material to hydrocarbon being mains> tained at about 6:1 with a contact time of about 10 seconds.

9. ille method inv accordance with claim l in Whiclithe sulrur dioxide and hydrogen sulfide. are reacted at temperatures Irom 500 F. to 150 F. in the presence or a catalyst capable oi' promot ing the ioi'mation oi' elemental suliur;

10. The method or continuously producing car bon disulfide by reaction or hydrocarbons and sul'iur, said hydrocarbons containing substan tial amounts 0I constituents tending to iorm dele- terious tarry suliur-containing by-products comm pi'isillg, contacting preheated nydl'ocarbonsv and preheated suliur vapors with an agglomerating. material in_a reaction zone under conditions ca pable ol tlieiormation oi- carbon usuliide and hy drogen sulfide;4 said agglomerating material being, capable 0Iv occludlngv said, Sulrurf-containing by products, sepa-rating carbon-_ disul1ide hydrogen sulfide, and said agglomerating material iroin. eacii other, subgecting saidagglomeratlng, ma. terial to an oxidizing atmosphere capable 01 pro-_ ducing sullur dioxide _ :rom said occluded by-4 products, reacting. said suliur dioxide and said Spaiated hydrogen sliliide under conditions ca. pable or forming elemental sulfur.

il. 'The method in accordance with vclaim 10 in which the agglom'erating matei'ialisv selected rrom tile group consisting o1 sintered alumina,_ silica,y diatoiiiaceousv eartn,_,sillca gel; activated. alumina', activated clays, and silica-alumina coin positions. _ v f l Y l _ Y _

iz. 'i ne-method,in_accordance with claim 10 in which the hydrocarbonisselectedrroin _the group consisting 0I' natural gas, propane, butane,` and their existing olennic homologues. and mixtures thereof. l _ _

13.. ',Lhemethod in accordancerwith claim 10 in which the carbon. disulfide vIorining reaction is. conducted ata temperature betweenwabout 842 l?. and 1500u Fi, and the ratio of agglomerating,

the. range of 2:1. material 11o-hydrocarbons is in to` 10:1.. p

i4. 'lhemethod in accordance with claim 10 in which the hydrocarbonsand suli'ur are pre heated _to reaction. temperature. _

15. 'I'he method in> accordance With` claim 10 in which the sulfur. is present in 4an amount be

" tween av lo. per cent ld_.en'ciencyand a ll) per cent excess of stolchiometric requirements for the re action _ __ _ _ _

lo. VThe method of converting hydrocarbons to carbon disulfide-by reaction with sulfur, said h_y drocarbons containing' constituents tending to formtarry suliur-containlng by-pioducts,l y coin piising passing preheated hydrocarbons and pre heated sulfur vapors into contact Withan ag glolneratlng; materialin areaction zone, said ag gloinei'ating material being capable of occluding saidsuliurscontaining by.-products and saidreac tion zone being maintained. ` under conditions to. promote the iormation` of carbon disulfide and hydrogen suliide,A separating said. agglomeratingY

2,666,696 13 I

material and the carbon disulde and hydrogen sulfide so formed, subjecting said agglomerating material to regeneration in an oxidizing atmos phere.

17. The method in accordance with claim 16 in 5 which the oxidizing atmosphere is an'oxygen containing gas. Y

18. The method in accordance kwith claim 16 in which said agglomerating material is a cat alyst capable of promoting the formation of car- l0 bon disulde from said hydrocarbons and sulfur.

HILLIS O. FOLKINS. ELMER MILLER. '

HARVEY HENNIG.

14 `References Cited in the le of this patent

Number 2,187,393 2,330,934 2,389,810 2,480,639 2,487,039 2,530,243 2,556,177

UNITED STATES PATENTS

Name Date De Simo> ______ _'_____ Jan. 16, 1940 Thacker __________ __ Oct. 5, 1943 Odell et al. ______ __ Nov. 27, 1945 Ferguson ______ __ Aug. 30, 1949 Belchetz ________ __ Nov. 8, 1949 Holder __________ __ Nov, 14, 1950 Gamson _________ __ June 12, 1951