US2519587A - Desulfurizing hydrocarbon oils - Google Patents

Description

Aug- 22; 1950 D. A. MGCAULAY ETAL 2,519,587

DESULFURIZING HYDROCARBON OILS Filed June 18, 1947 2 sheets-sheet 1 x if n STRlPP/A/G ZONE 34 `S21/fur Compounds Aug 22,1950 D. A. MGCAULAY ETAL 2,519,587

DESULFURIZING HYDROCARBON OILS 2 sheets-sheet 2 Filed June 18, 1947 Patented Aug. 22, 195o l DESULFURIZINGv HYDRlOCARBON OILS Davia A. Macaulay, chicago, 111., and Arthur P.

Lien, Hammond, Ind., assignors to Standard Oil Company, Chicagoylll., a corporation of Indiana Application June1s,1947,seria1N0.'z55,45'z

This invention relates to a process for desulfurizing hydrocarbon oilsl More particularly it relates to a process Vfor the desulfurization ofl hydrocarbon oils containing hydrocarbon disuldes.

In ther petroleum industry a number ofnhydro` carbonoils are produced which comprise sulfur compounds, l including hydrocarbon disuldes. Particularly, the petroleum industry normally produces relatively light or low boiling hydrocarbon oils such as gasoline,naphtha, kerosene and heater oils which contain hydrocarbon disulfides. Thus, for example, mercaptan-containing (sour) gasoline condensed from natural gas, distilled from crude petroleum oils orY derived from petroleum oil fractions bycracking operations is ordinarily subjected to so-called sweetening operations in the course of which the mercaptans in the gasoline are converted to gasoline-soluble disuldes which are retained in the gasoline. Although hydrocarbon disuliides do not possess the foul odor of alkyl mercaptans, they markedly reduce the ability of lead alkyls such Aas leadv tetraethyl to increase the octanenumber of the gasoline or naphtha in which theyare present, i. e., they reduce the Vlead susceptibility of the. fuel.r It has been observed that of the various types of sulfur compounds, hydrocarbon disuldes appear to exert the greatest depressing eiiectA on lead susceptibility (W. A. Schulze and A. Buell, National Petroleum News, 27, No. 41, page 25V (October 9,1 1935.) Hydrocarbon disuldes are also undesirable components inhydrocarbon oils intended for ,use as `fuels 4for the reason @that in ,the combustion process they are converted to sulfur vdioxide which, with the water'genera'ted in the combustionof hydrocarbons, tends 'dto cause corrosion of metal surfaces with'which it comes in contact.

Accordingly, it is an object of our invention to provide a process for desulfurizing hydrocarbon oils comprising sulfur `.compounds including hydrocarbon disuldes. Y 'Another object ofv our invention is to provide a process for converting hydrocarbon disyuldes and oleiins contained in hydrocarbon oilsintovaluable chemical products which can be recovered Or'empIOyment in in-v dustry; An additional object is to provide a process for Vremoving hydrocarbon disulfides and equimol'ecula'r amounts of olnic hydrocarbons from-hydrocarbon oils containing them, e. g., gasolinev or kerosene.` A further Objectis to provide a methodifor removing hydrocarbon disulfides and otherHsulfur 'corripounds4 from light Claims. (Cl. 196--31) hydrocarbon oils without substantially remov ing low boiling mononuclear aromatic hydrocarbons which possess high octane number.

Onel more object of our invention is to provide a process for removing hydrocarbon disuliides from a hydrocarbon oil containing substantially no olenic hydrocarbons or containing an olefinicV hydrocarbon in less than an equirnolar amount based on its content of hydrocarbon disuldes; Still another object is to` provide a method of simultaneously. alkylating aromatic hydrocarbons contained in a light hydrocarbon oil with olelins and effecting the conversion of. hydrocarbon disuliides and other sulfur compounds contained therein to compounds which are preferentially soluble in liquid hydrogen ilu'- oride andare extracted from said oils by said liquid hydrogen fluoride, whereby both the clear octane number and lead susceptibility of the light hydrocarbon oil are improved. These and other objects of our invention will become apparent from the ensuing description thereof read in conjunction with the accompanyl ing figures.

We have observed that hydrocarbon disuldes are dissolved only to a limited extent by concentrated liquid hydrogen fluoride at normal temperatures'. However, we have discovered that hydrocarbondisuliides contained in a hydrocarbon oil can be reacted with olenic hydro-J carbons in the presence of concentrated liquid hydrogen fluoride to produce reaction products which appear to be almost entirely di-thioethers and which are extremely soluble inr concentrated hydrofiuoric acid at normal temperatures. Thus,- We have discovered a desuliurization process for' the removal of hydrocarbon disuldes from hydrocarbon oils in which process concentrated liquid hydrogen fluoridefunctions both as a catalyst'and as a solvent for the sulfur-containing reaction products,'i. e. as a desulfurizing agent for the hydrocarbon oil. 'The reaction which appears to take place may be represented as follows Y i R1 R1 Rl Rl R-s-s-R+R'1=af R-s-(lJ-J-s-R A l' if wherein each R represents a hydrocarbon radical (usually an alkyl radical) and each R' may be hydrogen or a hydrocarbon radical. Although. our invention may be applied tothe desulfurizaton of any hydrocarbon oil containing disuldes, it is believed thatits application will be of principal interest for the desulfuriaation of relatively low boiling hydrocarbon oils such as gasoline-s, naphthas, kerosenes. Our invention may, however, be applied advantageously to furnace oil and the like.

Light hydrocarbon oils obtained from sour crudes contain a variety of alkyl mercaptans, including methyl, ethyl', nand iso-propyl, nand iso-butyl, nand iso-amyl mercaptans and smaller amounts of higher alkyl mercaptans such as hexyl, heptyl and octyl mercaptans. In the' sweetening process these rnercaptans are converted to symmetrical and unsymm'etrical alkyl disuldes.

In addition to hydrocarbon disulfides the hy' drocarbon oil to be treated may containaromatic hydrocarbons, particularly relatively 10W boiling mononuclear aromatic hydrocarbfvmsfv such as benzene, toluene, Xylenes, ethylbenzene, ethyltoluene, propylbenzene or butylbenzenes, and" mono-olenic hydrocarbons, in addition to the saturated. hydrocarbons; surprisingly, thesel aromaticsare' soluble only to avery; minor extentv irr liquid hydrogen;k iiuorid'e.` at ambient tempera.-

tures. Thus, gasolinas produced by thermal cracking'of gascoils or other high'b'oilfing frac-- tions of. crude oil: which. have been sweetened. by some conventional process such as doctor sweetening, or by copper-salts adsorbed on clays, contain hydrocarbon. dis-ulldes, olens: and usu-` allyr-v some aromatic hydrocarbons such as ben'- zene, toluene. and the'v like: Concentrated. sulfuri'c acid, e. g. 90' to 98 Weight. per cent sulfuric acid, in theY absence` of' olefins, converts mercaptane-'in'. hydrocarbon cils to disuldes1 and extracts a'fp'ortiori. of the disuldes. Gasolines derivedfr byY condensation from soury natural gas or. by non-cracking; distillation-. url crude petroleum, followed bya svveeten-ingi operation, con.- tairrhydroca-rbon disulfides" but little? or. no ole#- n'icf hydrocarbons..

In applying our invention to hydrocarbon charging stocks; containing disulfides: but noL ole.- nic. hydrocarbons; or less. than arr. equimolar' amount of olenic hydrocarbons basedonthe` disulde'content of: the charging stock, it will be necessary to treat thel charging stockA with: concentratedffliquid. hydro-gen uoride and arri added olen in quantity such that the: total olen. available for reactionzwith: thev hydrocarbon disulfide' is'atwleast equ'imolar with; respect to the: disulfide. Thus" in desuliurizing straight: run, sweetened gasoline or kerosene it is necessary to reactv the' charging' stockV with addedi olefin. in:Y an amount equimolar with' the amount of hydrocarbondisulde contained in? the. stools. When the' amount of mono-oleriichydrocarbons containedinl the charging stock exceeds thehydrocarbon disulfide content of the stock, .the treatingcon'- ditions may beadjusted (by control of ther amount' of hydrogen iluoride, temperature and time) to effect the. disuli'ide-olen` reactionand extraction. describedfabove without causing substantial polymerization or other react-ion ofthe olefinic hydrocarbons present in the charging stock in. excess of the amount of hydrocarbon di- A` Wide variety of mono-olenichydrocarbons may be" added to the disulde-containing chargingstocks ltovr adjust the'disuliid'e: olefin mole ratio` to about 1. Either individual. olefinsor mixtures of olensmay bei employed'. Mixtures ofolens with saturated` hydrocarbons, e. g. as found-in petroleum reinery fractions,` may likewise be employed.

Thusf the invention may be' practiced-v with tetra-isobutylenes;

4 acyclic mono-olenic hydrocarbons, such as ethylene, propylene, 1- or 2-butene, isobutylene, pentenes, hexenes, decenes, dodecenes, cetenes, styrene, vinylacetylene, alpha-alkyl styrenes such as alpha-methyl styrene, alphaor beta-vinylnaphthalenes; polymers of the above and similar olens, for example diisobutylene whichy is a mixture of 2,4,`4,-trimethyl-1- and 2-pentenes, propylene or isobutylene trimers and tetramers, and the like. The olenic polymer employed may be depolymerizable under the reaction conditions to yieldithe monomeric olefin which Will then enter intoreaction With. the' hydrocarbon disulde.

We) may also employ cyclo-oleflns, e. g., cyclohexene, methyl cyclohexenes, cyclopentene, methylcyclopentenes, terpenes, 3-vinylcyclohexene., cyclohexadiene-1,3, p-benzoquinone.

Poly-olens may also be employed in this inventi'on; for example LS-butadiene, isoprene, 2,3- dimethyl-LIE-butadiene,` cyclopentadiene, dicyclopentadiene'; l.,4-pentadiene,. L-hexadi'ene, divnylbenzene and the like? Wemay al'soemploy a. variety of substituted oleflns in. the practicevoi'. this invention, for example dichlorostyrenes, trifluoromethylvinylbenxzeries;v vinyl heteriocycliccompounds such as vinylthioplienesg. vinylfuranes and vinylp'yridines'; methyl'vin'yl ketone', vinyl acetate, esters of vcr'otonic,acrylic, metliacrylic or sorbic acids',v etc;

The process of the present inventionmay beI practiced not only with ol'en'ic compounds but' also with materials'capable of yielding these compounds under certain reaction conditions. Thus, ashas been pointed out above, depolymerizable polymers may beemployed asa source of `oleiinV monomer for the" reaction with a disuld'e: Examples of such polymers are' di, trior In the presencel of acidic condensation' catalysts certainV highly branched chain paraf'linic hydrocarbons undergo cleavage tof'yield olenichydrocarbons.. and may be employed as a source of olens for the 4present invention; a suitablel example ofsuch' a highly branched chain paraffin hydrocarbon is commercial isooctane which comprises predominantly 2,2,4-trimethylpentane. Cycloalkanes of highly strained ringstructuresuch as cyclopropane and substituted cyclopronanes. c.` g.. methylor ethylcyclopropane, can function as` a source of propylene or substituted propylenesy in the presence of acidicI condensationcatalysts.

Certain derivatives of olenhydrocarbons are unstable in. the presence of acidic condensation. catalysts and are capable of yielding olensintheir presence. This isespecially true of derivatives`V of tertiaryv olens. These derivatives comprise mercaptans, alcohols, ethers, halides and the like. Examples are tert.butylmercaptan, ethanol, isopropanol, tert-butanol, 4di-tertfbutyl ether, tertiary octyl chlorides,tert-methylcyclopentyl chloride, tertQ-butylchloride,` tert-amyl chloride.

We prefer to carry out tbe process of our invention` with commercial, liquid, substantially anhydroushydrogenfluoride. However, the inclusion of relatively -small amounts of WaterV inV the solvent-catalyst may be tolerated; thus the liquid hydrogen uoridef solvent-catalystV may contain up to' about l0 Weight per cent of Water. In general, vvaterv tends to reduce theV solvent capacity of hydrogen: fluoride for Sulfur compounds; therefore,v we prefer to employ substantially anhydrous liquid hydrogen. fluoride or s: hydrogen fluoride containing ino more than about 5 weight per cent of water. l. .l The amount of hydrogen fluoride employed will varyf .somewhat with the particular charging stock, temperature, other operating. conditions andthe results sought.` However, we ordinarily employ atleast sufficient hydrogen fluoride to i form a distinct acid phase, i. e., a phasein which liquid hydrogen fluoride is the predominant component. We may employ 5 to 100 per cent of commercial liquid hydrogen fluoride or even more,v based on the volume of the hydrocarbon charge stock; ordinarily we employ betweenv about l0 and about 30 volume per cent of liquid hydrogen fluoride based on the volume of the hydrocarbon charging stock.

It 'may sometimes be desirable 'to effectreaction of hydrocarbon disulfldeswith olefins and extractionof'the reaction products, respectively, in twodistinct stages. In` the first stageithe'reaction between a hydrocarbon disulfide and an olefln'maybe effected in the presence of a small, catalytic amount of concentrated vhydrogen fluoride insufficient to function efficiently as a solvent for the reaction products;A for example, the reaction may be effected with between about 116 and about 5 volume per cent of liquid hydrogen fluoride based on the Volume of the hydrocarbon charging stock.` When hydrogen fluoride is employed as a catalyst only it is preferred to employ an'A amount at least equimolar withrespect to the "amount of hydrocarbon disulfidej contained in the hydrocarbon charging stock. In the second (extraction)` stage, additional concentrated liquid hydrogen fluoride is added to the reaction mixture derived from the flrst stage in an amount suflicient at least to form a distinct acid phase. The acidphase contains the su1fur`"ontaining reaction products,l predominantly d thioethers. When-reaction and `extraction ar ffected as distinct operations it may be desired'g-to conduct each `operation at a different temperature. Thus reactionmay be effected at normalor elevated temperatures, for example, temperatures from about 50 F. to as high as about 250.*s F. and extraction may be effected at normal or reduced temperatures, for example, temperatures from 100'.F. down to 0 F. or even lower; for example Where olefin addition is necessary, the olefin may be added before, during or afterv the addition of the hydrogen fluoride to the clljarging stock. It is not necessary to employ pure olefins.

Ordinarily we may effect the desulfurization operation at ambienttemperatures', although the temperature may be varied over rilbroad range, for example betweenvabout 0 F. and-,about 200 Usually the process of the invention is con-J ducted at temperatures between about 50 F. and about 100 F., for example between 'about 60 F. and about 80 F.

The reaction between a hydrocarbon disulfide and a mono-olefinic hydrocarbo'niis exothermic and ,rapid at about room temperature. Accordingly, dependent upon the particular temperature HFzoil ratio, disulfide concentration in the oil,fintirnacy of contacting, etc., tlileriod of contacting between the hydrogen fluoride, olefin and disulfide may be varied fromfabout 1 minute or even less to about 10 minutes 1,

Suilicient pressure is maintained in the contacting-zone and in thezoneallwhere the acid phase is separated from the desulfurized hydrocarbon 'charging Vstock to maintain at least a substantial proportion of the VVhydrogen fluoride and A'charging stock in the liquid phase. 'Ordinarily pressures between about 0y and about 200 p; s. ijg. are suitab1e,ie. g. a pressure of about 25 or 50 pgs. i. g. i i

Thecontacting and acid separation equipment heretofore` employed in I-IF-catalyzed alkylation of isoparailins with olens can be employed in the-practice of this invention. Thus the charging stock, hydrogen fluoride and added olefin (if any) can be passed through a coil, which may be provided with baffles to induce mixing, and thence into a gravity settler or centrifuge; the `coil may be immersed in a heat transfer bath to' provide for removal of the heat generated in the reaction and to maintain the reaction temperature within desired limits. In another mode of operation, the charging stock, hydrogen fluoride and added olefin may be pumped through orifice mixers, venturis' 'or' other mixing devices andthence into a gravity settler or centrifuge for effecting separation of desulfurized hydrocarbon and an acidv phase containing extracted sulfur compounds. Other equipment and process flows will be specifically described in conjunction with the accompanying figures. In the specific embodiment of our invention schematically illustrated in Figure 1, the con'- tactor I0 is provided with a heat transfer jacket Il through which a cooling fluid is circulated during the contacting to remove heat generated bythe reaction, thereby maintaining the contacting temperature within the desired limits. In order to effect intimate mixing, contactor I0 is provided with motor-driven stirring paddles I2.

The hydrocarbon charging stock containing hydrocarbon disulfldes, e. g., a sweetened, straight run" gasoline containing substantially no oleflnic hydrocarbons is passed into the contactor through valved line I3. A mono-olenic hydrocarbon, forV example a refinery ethylene, propylene or butylene fraction can be charged into the contactor -through valved line I4. If desired part or all of the olefinic material may be premixed with the hydrocarbon charging stock so that a blend of olefln and hydrocarbon charging stock will be charged to the contactor through line I3. It is preferred to charge an amount of olefin substantially equimolar with the amount of hydrocarbon disulfide contained in the hydrocarbon charging stock in order to achieve thoroughgoing desulfurization of said stock. However, it will be appreciated that less than an equimolar amount of olen may be employed in any one contacting stage and that a number of contacting stages may be employedwith the addition of olefin in `each stagel Ordinarilyit is undesirable to add more than an equal amount of olen to the charging stock, unless it is desired also to effect olen polymerization to increase the yield of hydrocarbon" product from the desulfurization process. Also, it may be desirable to add more than an equimolar amount of olefin, based upon the amount of hydrocarbon disulde, whenit is desired to effect alkylation of aromatic hydrocarbons or isoparaillnic hydrocarbons which may be present inthe hydrocarbon charging stock.

Fresh concentrated liquid hydrogen fluoride is charged into the contactor from source i5 through valved line I6, e. g., in anvamount equivalent to about 20 per cent by volume based on the volume ofl `hydrocarbon charging stock. It is desirable to favoid extensive or prolonged contact of the liquid hydrogen fluoride with the olefin in the absence lof the charging stock containing hydrocarbon fdisulfldes'since contact may lead to unastenerdesirable' rea'ctionsVv such? fas" olefin polymerization accompanied. by hydrogen disproportionation", whereby the effective concentratioxr'ofolen is appreciably reduced in the contactirigpzone".

,.'In' contactorlf'the charging stock; vo'leiirr1and hydrogen fluoride are' agitated at a rate sucient to' cause intimate admix'ture at a -suitabletenie perature, for example about 60 F..toabout 86 Ff for a" suitable peri'od1,.'.for example' about I hour, and are theni dischargedv through valved lin'e l1 into a cooler `Iii where the temperature of the mixture 'is adjusted to a` desirable 'value for. the? subsequent' step of separating the hydroe carbon and` acid phases. desired, additional concentrated liquid' hydrogen.' iiuoride may be' added-to the mixture in line l1" through' valved line 191' From cooler t8 themixture' passes Vthroug'hilline zfixintoa sett1er'2l wherein desulfurize'd hydro# carbons arevsepar'ated from a liqu'idhydrogenl fluoride phasecontaining sulfur compounds. though' thesettleris depicted as a gravity settler, it-:will be appreciated that a` centrifuge couldbe employed instead. If desired,- thesettler may be provided with packing to serve as an aid to'strati-- ication'.: Suitable packing materials comprise shapedfragments of carbon, coppen'Monel' metal, carbon steel and certainl magnesium alloys con tain-ing'minor amounts of aluminum and still smaller amounts of otheralloyingelements such as zincfor manganese'. (Dowmetals). The-settler' isequippe'd with an overheadvalved Vent line 22 through which 'light gases maybe released to adjust the pressure to a desired value. Suitable operatingl conditions for the settlercomprise" a n is vaporized, optionally at pressures below atrnfos phericand/or with the aidot stripping gases asmethaneg. ethane-,fpropane; bu-tane, permane,-V etc: From theY stripping zonethe hydrocarbon passes throughl valved line 275y tot storage or. tot such ulterior treatment,- e. g.r, neutralizationfvas.may be desired.

' Residual hydrogen' fluoridernay be .removed from the hydrocarbon oil by washing-with alka-f linemateria-ls,` e.v g; caustic'soda; by ypassage over metal uori'des, e. g., sodium'or potassium uorid-es or hydroiuorides; by passage over'adsorp'a tivematerials such as-activated alumina, chrom; iuinr 0Xicle---alurnina,v silica gel;- activated-carbon and the like.

When unsaturated hydrocarbon charging stocks are employed, alkyl 'uoridesare-usually formed therein. The alkyl uoridesf have detrimentalE ef.-` tectsoni the octane number of hydrocarbon fuels and should bel'removed therefrom. number. of methods are amai-labile iordeluorination, includ;- ing high temperature treatmentwith bauxite and thelike..

.f "Eher 'acid :phase `isf discharged from' the settler through .valved line 28, whence partV or all thereof may be recycled to 'contactor 'Id through Valved liner` 2l, heat exchangerv 28% inl which its tempera ture 'is brought tothe desired value for the con: tac'ting operation', and valved linelt'. It is desirable to pa'ss` atleast a partr of the acid: phase fromthe settlerrthrough Vals/,fed line; 29' and heaterY filito' a;- Zorre Ltlief'hydrogeir fi'uoridezand sulfur compounds in solution `therein are' sepafr rated 'f v3;' v`i Whei the recovery of hydrogenffiuorideais'une important andthe' -principal object is' tdseparate the' sulfur compounds, the` acid may bel diluted with water onneutrahZedQwhereupon the-suitorcompoundanotably di-thioethers, separate' as an immi'scible liquid phase which may be washed with Water'and.fractionate-dintoclose lboiling fractions which'fmayhave industrial value; Ordinarily 'it isdesirable to .separatehydrogen fluoride in suit-I able formz-forireuse irrzthe contacting.; operatioi'ii It is; therefore', desirable tosubiecttheacid phase frottis-the ,settler .tof aA fractionation operation.l This may be effected in` fractionator 3'I Inor'der to aidthe vaporizationand withdrawal oi hydrogen. fluoride-zr," a; stripping gas," whiclfr mayy form a/minimum-yboiling` azeotrope withchydro-gen flu--r oridev mayfbe :introduced intol the. lower portion ofitheiractionatorthrouglr Valved line .32; Suita abile"-stripping` gases include' methaner-ethane-, propane, butanestandf pentanesi` If desired frac'a tionator 3! may be operated at a subatmospheric pressure- V Hydrogenrluoride is vaporizedfin: the

tractionator and. passes i overhead through v-valved line-33 for condensation and reuse-in contacter l0.

The higher boilingsulfur compounds are withdrawir from the fractionator through-valved line tdi 'Iv-hey may be freed lfromv traces oi acid-by` washing withalkaliesf-andwater or by passage over materials capable ofadsorbing orcombi-ning chemically with: hydrogen fluoride Figure-f2 illustrates another embodimentzoi our invention wherein counterow contacting of. the" hydrocarbon charging stock with liquid hydrogen fluoride and separation of a desulfurized hydrocarbon phase and an; acid phase enriched in sulfurzc'ompoun'dsware effected in one tower. Desuldr furizatioir tower HI8 is provided with contacting means iol', for example shaped-:packing vmaterials such as fragments of carbon, copper, -Monel metal, carbon steel, magnesium alloys, etc.A Heat" exchange coils m2 -are provided in the contacting section ofthe tower to aid in' controlling the temperature.; Hydrogen uori'de is admitted into the tower from Ya source'such as storage tan-ky H13; valvedline l Slt and line |05, passing into the upper portion of the contacting zone inthe tower, whence it passes-.downwardly'to-the lower end. of the-tower. The-hydrocarboncharging stock containingV hydrocarbon Adisuliidesis passed into the lower portion toi the contacting zone inthe tower throughvalvedli-ne' I o5 and rises thro-ugh the contactingr zone `against the -counterflow oi' liquid hydrogen uor-ide. The desired amount 'oi olefin is added i to v the hydrocarbon charging stock throughpva-lved line i'l, The upper end oi the' tower, above the contacting zone-serves1asasettling'zonefor. the desuliurized or partly' desul furized hydrocarbon charging stock'which-is'withA drawn .therefrom through' valv'ed line mit; whence it may 'be withdrawn through l'iydrogenfluoridestripping zone tti-Siandidischarged from ther system through.lineflfMl.: It isusually desirable to 'neue tralize traces ot, hydrogen uoride which Iiiay` be containedirr the?y oilfleaving the system through 1in@ Y Y Partf of the 'partly' desulfurized hydrocarbon stock may be recycled tothe vcontacting zone in tower I through-valved line i i I, Vheat exchanger I IEfand valvedlined-llt.AA TheV acid containing' dis# solveds'ulfur compoundssettles into' the lowermost portion of tower it whence: it iswi-thdrawn through .valvedline H3; and may: be recycled to diaria? the contacting zone through'pum'p'fl I4, valved line |,I 5, cooler IIB and line |05. It is, however, desirable to pass part or all of the-acidy phaseI from tower through valved line II1 and heater II'8 into a fractionator': I I9." lIn the fractionator, hydrogen fluoride is vaporized and passed overhead through Valved line |20, whence at least a .portion of the hydrogen iluoride vapors maybe removed from the 'system' through valved line I2| preferably part or all of l; the `hydrogen c uoride vapors are passed through valved line"V |22r and condenser |23 foi1 recycle'throughlline A,|05 tothe desulfurization tower |00. Toaid in the v'aporiation of hydrogen fluoride in the fractionator, a stripping gas is passed through valved line |24 and/or the fractionator may be operated at a subatmospheric pressure. Sulfurcompounds are withdrawn from fractionator ||9 through valved line |25. Gases which may accumulate in the system may be removed from the desulfuri'zation Vtower |00 through a valved vent line |26.

The following examples are introduced in order to illustrate but not unduly to limit the scope o the process of this invention.

Example 1 A solution of n-octyl disulde and n-heptane was prepared containing 1.50 weight per cent of sulfur. This solution was agitated for 1 hour at room temperature with 200 cc. of commercial liquid, substantially anhydrous hydrogen fluoride per liter of the solution, ,after which agitation y was discontinued and the contacting mixture was allowed to separate by gravity into an upper hydrocarbon phase and a lower acid phase. Sulfur analyses of the phases indicated that only 9 v weight per cent desulfurization of the n-heptane had occurred. Under otherwise identical operating conditions but with the addition of 1 mol of diisobutylene per mol of disulde contained in the n-heptane, 95 per cent desulfurization of the n-heptane occurred. Since diisobutylene depolymerizes readily, one mol thereof can be considered as the substantial equivalent of two mols of isobutylene. It is apparent that the disulfide reacts with the olefin to produce a sulfur compound which is far more soluble in liquid hydrogen fluoride than n-octyl disulfide, which under the conditions lof this experiment was relatively insoluble in liquid hydrogen fluoride. It appears that the HF-soluble sulfur compound which is produced when an olefin is added is a di-thioether.

Example 2 indicated that 99 weight per cent desulfurization of the n-heptane had occurred. In the absence of an added olefin desulfurization to the extent of only about 60 weight per cent could be expected.

Although we have speciiically described the desulflurization of hydrocarbon oils containing hydrocarbon disul-des by reaction and extraction with liquid hydrogen iluoride and a, mono-olenic hydrocarbon, it will beappreciated that other organic compounds containing olefnic unsaturation .might be ,used instead. Although we have emphasized the reactions of ,hydrocarbon disulfides with olens in the presence of liquid hydrogen fluoride as. a catalyst and solvent for the product, it is appreciated thatthe liquid hydrogen-fluoride may exert more or less solvent` capacityl for other sulfur compounds which may b e presentiin thechydrocarbon chargingstock, .for

example thiophenes, Athiophanes or, thioethers.

Mercaptans react with olefins in the presence of liquid hydrogen uoride as a catalyst-solvent to form thioethers which are extracted by the hydrogen fluoride from the hydrocarbon charging stock.l Thioethers are far more soluble in liquid hydrogen fluoride than the correspondingmer- Captaris...` i

The general reaction of organic disulides with-: olenic hydrocarbons in the presence of chemical compounds'which are acidic chemiical condensation catalysts to effect the preparation of dithioethers is claimed in applicants copending application for U. S. Letters Patent, Serial No. 755,456, filed of even date herewith.

Having thus described our invention, what we claim is:

1. A process which comprises sweetening a mercaptan-containing hydrocarbon oil to produce a, hydrocarbon oil containing disuldes, adding an olenic hydrocarbon to the sweetened oil in an amount sufficient to increase the molar ratio of olenic hydrocarbons to disuldes to at least one, contacting the sweetened hydrocarbon oil in the presence of said oleflnic hydrocarbon with liquid hydrogen fluoride in quantity sucient at least to form a distinct liquid phase at a ternperature between about 0 F. and Vabout 200 F. under a pressure sufficient to maintain the liquid phase, thereby effecting chemical reaction between said disuldes and said olenic hydrocarbon to produce a hydrogen fluoride-soluble sulfur-containing reaction prod'uct, and thereafter separating a hydrocarbon oil of reduced sulfur content and a liquid hydrogen fluoride solution of said sulfur-containing reaction product from the mixture produced in the contacting operation.

2. A process which comprises sweetening a cracked sour hydrocarbon oil, adjusting the olefinzdisulfide molar ratio of said oil to about one and contacting said oil with liquid hydrogen uoride in quantity sufficient at least to form a distinct liquid phase, thereby effecting chemical reaction between said disulfide and said olefin to form a hydrogen uoride-soluble sulfur-containing reaction product, and thereafter separating a hydrocarbon oil of reduced sulfur and olefin content and a liquid hydrogen fluoride solution of said sulfur-containing reaction product from the mixture produced in the contacting operation.

3. In a multi-stage process of removing a hydrocarbon disulfide contained in a hydrocarbon oil, the steps of contacting said hydrocarbon oil in a plurality of stages with concentrated hydrogen uoride in quantity sufficient at least to form a distinct liquid phase with an added olefinic hydrocarbon in an amount such that the olefinic hydroearbonsdisulde molar ratio is less than one in any stage but the total olefinic hydrocarbomdisulde molar ratio in all the stages is atleast one, effecting chemical reaction between said disulfide and said olefinic hydrocarbon in each stage to form a hydrogen fluoride-soluble sulfur-containing reaction product, and withdrawing from the process a hydrocarbon oil substantially free of said hydrocarbon disulfide and

Claims (1)

1. A PROCESS WHICH COMPRISES SWEETENING A MERCAPTAN-CONTAINING HYDROCARBON OIL TO PRODUCE A HYDROCARBON OIL CONTAINING DISULFIDES, ADDING AN OLEFINIC HYDROCARBON TO THE SWEETENED OIL IN AN AMOUNT SUFFICIENT TO INCREASE THE MOLAR RATIO OF OLEFINIC HYDROCARBONS TO DISULFIDES TO AT LEAST ONE, CONTACTING THE SWEETENED HYDROCARBON OIL IN THE PRESENCE OF SAID OLEFINIC HYDROCARBON WITH LIQUID HYDROGEN FLUORIDE IN QUANTITY SUFFICIENT AT LEAST TO FORM A DISTINCT LIQUID PHASE AT A TEMPERATURE BETWEEN ABOUT 0*F. AND ABOUT 200F. UNDER A PRESSURE SUFFICIENT TO MAINTAIN THE LIQUID PHASE, THEREBY EFFECTING CHEMICAL REACTION BETWEEN SAID DISULFIDES AND SAID OLEFINIC HYDROCARBON TO PRODUCE A HYDROGEN FLUORIDE-SOLUBLE SULFUR-CONTAINING REACTION PRODUCT, AND THEREAFTER SEPARATING A HYDROCARBON OIL OF REDUCED SULFUR CONTENT AND A LIQUID HYDROGEN FLUORIDE SOLUTION OF SAID SULFUR-CONTAINING REACTION PRODUCT FROM THE MIXTURE PRODUCED IN THE CONTRACTING OPERATION.

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