US2953606A

US2953606A - Production of isohexane and cyclohexane

Info

Publication number: US2953606A
Application number: US698607A
Authority: US
Inventors: Lloyd E Dean; John L Groebe; Fred S Ivey; Thomas C Flavin
Original assignee: Phillips Petroleum Co
Current assignee: Phillips Petroleum Co
Priority date: 1957-11-25
Filing date: 1957-11-25
Publication date: 1960-09-20
Anticipated expiration: 1977-09-20

Description

.mi Y S INVENTORS L.E.DEAN J.L.GROEBE T.C.FLAVIN F.s|vEY ATTO@ EVS L. E. DEAN cru. 2,953,606

PRODUCTION or ISOHEXANE AND cYcLoHExANE:

3 Sheets-Sheet 1 .DON

. v S x @055m v d om m mm( mm man Ehm I L uw. w. wm vv .vnr D IIIIHHN" a otmw m uv J.\ wmnmmazmb Io.: .VMT .illl vm f ui E m @n mm Nv I. Il o V ow me m @N d h1 Sept. 20, 1960 L. E. DEAN l-:rAL

PRODUCTION OF' ISOHEXANE AND CYCI..()I{EIXAI`1E 3 Sheets-Sheet' 2` Filed NOV. 25, 1957 Sept. 20, 1960 l.. E. DEAN ETAL PRODUCTION' oF IsoHExANE AND cYcLoHExANE 3 Sheets-Sheet 3 v Filed NOV. 25, 1957 dm-Dm KOPOE mwN OmN ON N NON T.C. FLAVIN F.S. lVEY M ad A T TORNE PRODUCTION oF IsorrExANE Annv cYcLoHExANE Lloyd E. Dean, 'John L. Groebe, Fred S. Ivey, and Thomas C. Flavin, all of Bartlesville, Okla., assignors to Phillips Petroleum Company, a corporation of Delaware Filed Nov. Z5, 1957, Ser. No. 698,607

Claims. (Cl. 260-6'66) This invention relates to .an improved process for the conversion of hydrocarbon-s. In one vaspect it relates to a process for the isomerization ofnormal acyclic and alkyl substituted alicyclic hydrocarbons having similar boiling points, such as normal hexane and methylcyclopentane. In another -aspect it relates to a combination process for the isomerizat-ion of a feed material comprising normal hexane, methylcyclop'entane and containing impurities, such as sulfur and ibenzene in the presence of a metal halide catalyst.

This application is a continuation-impart of L. E. Dean et al., Serial No. 652,944, iiled April l5, 1957, and now Y abandoned.

Various hydrocarbon fractions of .petroleum contain large amounts of naphthenic compounds and normal paraflins. Many of these compounds are relatively useless Ain their original form; however, they can be converted to valuable materials which are useful in motor fuels or as starting materials in chemical processes. Thus, for example, normal hexane which has a low octane number can be converted to isohexanes which have high octane numbers and form valuable components )of motor fuels.A

Another object lof this invention is topprovide an irnponents normally present in motor fuel. Y

Still another object of this invention is to provide an proved process for increasing the octane number of c omimproved process for the isomerization of normally acy. 1

clic and substituted alicyclic hydrocarbons having similar Y boiling points.

Yet another object of Ithis invention( is tor provide ian improved process for the isomerization of a feed material comprising normal `hexane and methylcyclopentane and' containing benzene and sulfur `as impurities.

These and other objects of the invent-ion willfbecome more readily apparent `from the following detailed description and discussion.

The above objects are vachieved broadly by contacting' a feed material comprising -a normal Iacyclic and an alkyl substituted Ialicyclic compound with a metal halide isomer-ization catalyst and a corresponding hydrogen halide under suitable conversion conditions whereby said compounds are isomerized. Y

In one aspect of the invention the feed material comprisi-ng a mixture of compounds of similar boiling points such -as normal hexane and methylcyclopentane.

In another aspect of the invention the feed material which contains impurities, such as benzene yand sulfur,:

is hydrogenated in the presence of a nickle catalyst Wherevby the benzene is converted -to cyclohexane and the sulfur is converted to nickel sulfide after which said feed material is isomerized.

Isomerization of normally -acycl-ic and alkyl substituted alicyclic hydrocarbons in the methodof this`"ivetion 4 2,953,606 Patented Sept. v20, 1960 is carried out usually at a temperature in the range of -rbetween about F. and about 160 F., the particular temperature employed being dependent on the composition of the material to be converted. lVarious normal acyclic'` compounds can be isomerized, including normal butane, normal pentane, normal hexane, normal heptane, etc. The alkyl substiuted alicyclic compounds which can be isomerized include methylcyclopentane 'which is isomerized to cyclohexane, 1,1-dimethylcyclop'entane which is converted to methycyclohexane, and the like. Isomerization reaction is preferably carried out under sufficient pressure to provide a liquid phase reaction namely a pressure in the range between about and about 300 p.s.i.g. The contact or residence time of the reactants in the reactor varies usually between about 0.1 and about 5 hrs.

' The ycatalyst employed in carrying out isomerization comprise metal halides, such `as aluminum chloride, aluminum bromide, boron triuor-ide land the h-alides of such metals as zinc, tin, arsenic, antimony, zirconium, beryllium, titanium, iron, and the like. These catalysts are especially effective when present as complexes which are formed by interaction between the metal ha-lides and hydrocarbons present in the reaction system. A particularly desirable isomerization catalyst is the complex of hydrocarbon with aluminum chloride. In addition to the catalyst it is desirable that the corresponding hydrogen halide be present in the reaction zone since this material maintains catalyst activity at a high level. The reaction rate and the conversion of the hydrocarbon feed is dependent on the amount of aluminum chloride in the Aaluminum chloride-hydrocarbon complex. Thus, to maintain a norm-a1 hexane conversion of about 55 percent, the catalyst complex should contain 60 to 62 percent aluminum chloride. p However, the quantity ofalumium chloride in the complex can be varied over wide ranges to provide a corresponding rang of feed reactant conversion. While the over-all yactivi-ty of the catalyst is .established by the arlurnium chloride content, as stated,

' cent of the feed with about 4 Weight percent being preferred. The hydrocarbon-to-catalyst ratio is also an important factor in the isomerization reaction rateand :generally this ratio is maintained between about 0.8:1 'and about 1.4:1 although ratios `as high as 5v -to l can rbe used if reaction temperatures are increased. y

The removal of contaminants, namely benzeneand sulfunfromthe -isomerization feed is effected by contacting said feed with :a dehydrogenated nickel catalyst and hydrogen under suitable conditions of elevated temperature, usually between about 360 Iand about'SOO F. Pressure does not appreci-ably affect the hydrogenation reaction and the actual pressure employed is established principally by the partial pressure of the hydrogen present. Usually the liquid hourly space velocity is between `about l and `about 3 cubic feet of liquid feed per cubic -foot ofV catalyst per hour. Operation with an excess of ihy'drogenis preferred; therefore, it is desirable that more than the v3 mols necessary to convert each mol of'benzene be present in the reaction zone. Preferably, the hydrogen concentration is such as to provide a hydrovgen-to-benzene ratio of between about 4 and about v1,6

Ymols/ mol.

As a result of the preceding operationbenzene is hydrogenated and converted to cyclohexane, which is one `oi' the .desired products of the isomerizaton reaction; and

the sulfur in the feed material reacts with the nickel cat- 3 is necessary Yto withdraw and dump the spent catalyst and-add vfresh catalyst to thesystem.

In order to more fully describe the invention in its various process steps and to provide a better understandin g thereof, reference is had to the vaccompanying draw- -ings o'f which Figure lis adiagrammatic illustration of Vthe feed 'preparation unit and a benzene dehydrogena- `tion unit, vFigure 2 4is a diagrammatic illustration of van isomerizationunit andFigure `3 is a diagrammatic illustration of a unit for fractionating'etlluentfrom the isomv'erization unit.

yReferring to Figure 1 a feed material comprising a mixture of isohexanes, normal hexane, benzene, methylcyclopentane and cyclohexaneis introduced to a v,denormalhexanizer Sithrough conduit 1. In the denormalhexanizer ywhich is a conventional fractionating tower, the feed material'is separated'to provide an overhead product `which is concentrated in normal hexane and also contains ka ysubstantial quantity of methylcyclopentane. This material is passed from tower 3 inthe vapor state through conduit 5 and pump 7 into accumulator 9. Liquid is fwithdrawn from the accumulator through conduit 13 and utilized as reflux to the denormalhexanizer through conduit 15. A portion of the net accumulator liquid is removed as product; for example, for use as a solvent material, through conduit 19, and theremainderis passed `through

conduits

17 and 2, to the benzene hydrogenation Y'feedsurge tank 4.

'The denormalhexanizer bottoms which comprise principally `the heavier portions of the feed are lremoved through conduit 23 and combined with `a second hydrocarbo'n feed stream through conduit Z5. The `latter stream is similar in composition to the denormalhexanizer bottoms. The combined streams are introduced to fractionator 27 wherein a separation between the components of the feed is carried out to again provide an overhead stream concentrated in normal hexane and methylcyclopentane. This material is passed from the fractionator through conduit 29 and condenser 31 into accumulator 33. The accumulated material is returned in part to the fractionator through pump 35 and conduit 39 and the remainder is introduced to demethylcyclopentanizer 47 through conduit 41. In the latter vessel a further renement of the hydrocarbon feed is made whereby sulfurcontaining materials are rejected from the bottom of -the tower. The overhead material, which is concentrated in normal hexane and methylcyclopentane, is'condensed With a portion being returned'to the tower as reux through conduit 59 vand the remainder being combined with the overhead from the denormalhexanizer 3 through conduit 61. The bottoms from each of fractionator 27 and demethylcyclopentanizer 47 are joined through conduits 45 and v65 respectfully to `provide a combined stream'which iswithdrawn from the unit through conduits 67. Each of the `fractionators are provided with reboiling means, namely 21, 43 and 63,10 provide the heat necessary for the separation whichis carried out in each tower. As a resultof the aforedescribed steps there is provided in the benzene hydrogenation 'feed surge tank 4 a hydrocarbon mixture comprising normal hexane, methylcyclopentane and a small amount of benzene, cyclohexane and Various isohexanes. rThis material is removed from the feed surge tank and passed through `conduit 6, where it is joined by a combined recycle and make-up hydrogen stream, then through :exchanger 8 countercurrent to reactor effluent wherein -preheat .is added and then through conduit 10 into ,furnace :11 where the additional heat required to initiate the reaction is provided. The heated feed material leaves the furnace at a temperature of about 360 F., ,passesthrough conduit12 and enters reactors 18 and 18a. Thereactors are .arranged .so that the flow therethrough can -beinseries orin parallel, depending on whether or not a .reactor is withdrawnfrom service. Generally it is desirable to.,carry.out the hydrogenation reaction by passing the 'feed material through the reacto'rs in .series zene to form cyclohexane.

with the feed first passing through the reactor which is next'tobe regenerated and then through the other reactor. It is possible to make either reactor first in the series by a suitable arrangement of

valves

14, 14a, 16, 16a, 20, 20a, and 22 and 22a. In this

specific embodiment valves

14, 26, 16a and 22a are open and

valves

14a, 16, 22, and 20a are closed whereby the reactants ow through the reactor 18 fand then .through reactor 18a. "Within the reactors the principal reaction is hydrogenation of ben- This reaction is exothermic, therefore there is ,atemperature rise, usually of .about 2-1o Iper ,mol .percentof `benzenein the Vfresh feed to the reactor. In the event that sulfur or sulfur-containing compounds fare Vpresent iin the `feed material the sulfur reacts with thenickel catalyst converting the lcatalyst to nickel sulide. Since knickel sulfide does no't promote the hydrogenation reaction, removal of the sulfur from the feed in this manner in elfect poisons the catalyst, which necessitates periodic shutdown of each reactor for removal of contaminated catalyst and addition of fresh catalyst.

The effluent from the reacto'rs, now free from benzene and sulfur, but containing some light parafns as a result of a minor amount of cracking passes through conduit 24 andexchanger'S countercurrent to the feed to furnace 11 and then through conduit 26 into a high temperature separator 28. In thisV vessel the major portion of the hydro'genjn the effluent, plus uncondensed lighter hydrocarbons aregremoved, passing from `the separator through `conduit 30. The vapors from the separator are ,passed through a partial condenser 32 and into a gas scrubber 34 wherein a portion of thehydrocarbons are separated fromthe hydrogen by condensation. The remaining gaseousmaterial comp-rising `about mol per cent hydrogen is releasedfrom the scrubber through conduit 36 andcombined with the feed to the hydrogenation unit as previously described. As required make-up hydrogen is introduced to the recycle hydrogen stream through conduit 37. 'The liquid material from gas scrubber 34 is returned to the high temperature separator through pump 3S and conduit 40. As necessary to maintain a more or less constantlevel in said separator thecombined liquid is withdrawn therefrom throughconduit 42 and introduced to hydro'gen fractionator 44 supplied with heat through reboiler '57, whereinseparation and recovery of the remaining hydrogen in this material is eiected. The overhead 'from the stripper, which comprises principally hydrogen, with a small amount of light gaseous hydrocarbon'passes 'throughcondut 46 and partial condenser 48 into accumulator V50* vfrom which hydrogen is withdrawn through conduit 52. Condensed overhead is returned to the stripper through pump 54 and conduit 56 as reux. The bottoms from the hydrogen stripper cornprising a stream now essentially f-ree ,from hydrogen Vand light hydrocarbons are removed from the stripper through conduit 5.8, cooledin exchanger 60 and introduced to the isomerization vfeed surge tank 62. Before entering the isomerization feed surge tank the stripper bottoms eihuent is combined through conduit 220 with a stream rich in methylcyclopentane obtained in a manner hereinafter described.

In the /irst istage of the isomerization step the feed material is removed vfrom surge tank 62 through pump 64 and passed through conduit 66 into dryers 70 and 70a wherein any moisture present in the feed is removed. 4Normallythe dryers are operated in parallel with one dryer being in operation while the other dryer is being regenerated or being emptied and filled with fresh drying agent. Various drying agents can be employed'however, usually bauxite ispreferred. The dried feed is passed through cooler "74 where the temperature is substantially reducedand'then ispassed through conduit 76 into aluminum chloride saturator 7S. In this vessel the feed which can be introduced at variouselevations contacts aluminum chloride crystals which are picked up and carried with the feed through conduit 80 into an isomerization reactor `82. Before entering the reactor the catalyst concentration of the feed is increased by the addition of aluminum chloride hydrocarbon complex from settler 86. Hydrogen chloride is also added to the feed, through conduit 116. The principal reaction which takes place in the reactor is the isomerization of normal hexane to 2-methylpentane and methylcyclopentane to cyclohexane. In addition, three other isomers of normal hexane, neohexane, diisopropyl, and S-methylpentane are also formed in varying quantities. The effluent yfrom the reactor, comprising unreacted normal hexane, methylcyclopentane, cyclohexane and the various isohexanes is passed through conduit l84 and enters settler `86 wherein entrained catalyst complex is separated from the hydrocarbon material, the major portion of the settled catalyst complex being returned to the reactor through pump 88 and conduit 90. Inasmuch as the catalyst gradually loses its activity it is desirable that a portion of it be either .periodically or continuously withdrawn from the system.

For this purpose a baffle is provided in one end of settler 86 and separated catalyst is Withdrawn continuously therefrom through conduit 92. Although a substantial separation of catalyst and hydrocarbon is effected in settler 86 of the hydrocarbon effluent therefrom still contains finely divided aluminum chloride-hydrocarbon 4complex and a major proportion of the hydrogen chloride. This stream is passed through conduit 94 into

coalescers

98 and 98a for the purpose of effecting removal and recovery of these materials. As in the case of the isomerization feed dryers these vessels are operated in parallel with normally one vessel in operation while the other isv being emptied and refilled with the coalescing and filtering medium. Various inert materials can be use d for coalescing the catalyst, including sand, charcoal, and the like, however, bauxite is preferred for this purpose. The effluent from the coalescers, now substantially freed of aluminum chloride-hydrocarbon complex is introduced to hydrogen chloride stripper feed surge tank 104 through conduit 102. As previously stated, the eiuent from the benzene hydrogenation contains small quantities of light Vgaseous hydrocarbons which are the result of cracking during the hydrogenation step. 'Ihese materials are normally removed in the stripper along with said hydrogen chloride however, since the v hydrogen chloride is recycled to the isomerization reactor eventually the light gases build up in the system. To prevent such a buildup venting of gases is provided `through column 106 which is disposed on the stripper feed surge tank. In order to prevent loss of hydrogen chloride in this operation, Ybottoms from the hydrogen chloride stripper, comprising the main product stream '(substantially free from HCl) areV introduced to the top of column 106 through conduit 132. Hydrogen chloride inV the vent gases is thus absorbed and returnedto the stripperjfeed surge tank and the gases are passed from the system through conduit 108.Y

Accumulated materialrin the feed surge tank is removed therefrom through pump 110 and conduit 112, passed through exchanger 113 in indirect heat exchange with hydrogen chloride stripper bottoms and is introduced to hydrogen chloride stripper 114v wherein the major portion of the hydrogen chloride is separated from the reactor eluent. The overhead product from the stripper is a hydrogen chloride rich stream which, as previously noted, is returnedv in part to the isomerization reactor through conduit 116. The remainder of the stripper overhead is passed through condenser l118 and enters accumulator 120, from which it is withdrawn and returned to the stripper as reflux through pump 122 and conduit '124. 'Any heat required in the stripping operation is provided by reboiler 125 which is disposed in the bottom of stripper 114. The stripper bottoms product comprising principally the heavier hydrocarbon portion of the reactor eluent is removed therefrom through conduit 126, passed through exchanger 113 and cooler 128, conduit 134 and pump 136 and then introduced to caustic wash tank 138 wherein any remaining hydrogen chloride is neutralized. Provision is made to recycle caustic to the wash tank through conduit .1142, with spent caustic being withdrawn through conduit 140 and fresh caustic being introduced, as required, through conduit 144. The caustic washed hydrocarbon product is then passed through conduit 146 to sand towers 150 and 150a to remove the caustic. These towers are also operated in parallel in order to provide for continuous operation during dumping and replacement of the sand contained therein. From the sand towers the product stream is introduced to the .fractionator feed surge tank 154 through conduit 152.

The isomerization-fractionation system comprises a series of three fractionation stages, the rst two stages each being carried out in two fractionators and the nal stage being carried out in a single fractionator. In the first stage of this process material from surge tank 154 is passed through pump 156 and conduit l158 into a rst fractionator 166. Before entering the fractionator the feed passes through two

exchangers

160 and 162 being indirectly heated with the bottoms from

fractionators

166 and 190 in the exchanger 160 and further heated with steam in exchanger 162. Fractionator 166 is the first fractionator in the series of two which are provided for the purpose of removing isohexanes `from the isomerization reaction eluent.

A portion of the feed material is introduced to this fractionator through conduit 164. Within the fractionator a separation is carried out whereby an overhead product substantially free from normal hexane is provided. This material leaves the tower in the vapor state through conduit y16S, is condensed in condenser y170 and passes into an accumulator 172. Accumulated liquid is withdrawn through pump 174, a portion is returned to the fractionator through conduit 176 as reflux and the remainderis yielded from the unit through conduit 178. The yielded material, which comprises essentially isohexanes, has a high octane value and is suitable for use as aviation fuel.

The remaining portion of the isomerization effluent is passed through conduit 188 and introduced to the second deisohexanizer 190. -In this vessel it is necessary to provide a dilerent separation from that carried out in fractionator 166. Due to the reaction equilibrium in the isomerization reactor and they composition of the feed provided thereto, it is not possible to convert all of the normal hexane present in the feed to the reactor even though recycle of this material is employed. As a result, it is necessary to yield a quantity of normal hexane from the unit. This is accomplished by operating deisohexanizer 190 to provide an overhead stream containing isohexanes and in addition any excess unconverted normal hexane. The overhead product from tower'190 is condensed and a portion is returned to this tower as reflux through conduit 200 with the remainder being yielded through conduit 202. Since the material in conduit 202 contains a substantial amount of normal hexane it has a lower octane number than the overhead product from tower 166 and therefore is suitable only for motor fuel.

The portion of -the isomerization effluent which remains after the removal of normal hexane and isohexanes passes from the bottom of

deisohexanizers

166 and 190, through

conduits

182 and 206 respectively, through exchanger 160 and conduit 184 and then into accumulator 186. From this vessel the bottoms material is passed through pump 208 and conduit 210 to the second fractionation stage which is provided for the Ipurpose of removing unconverted methylcyclopentane and normal hexane from the reaction eluent. Two

fracftionators

216 and 238 make -up this stage.

'I 'he feed to these fractionators passes rst through.ex 'changer V212 in indirect heat exchange with the bottoms from the fractionators and then through exchanger 214 after which this material is divided with a portion being fed to each of the fractionators.

The overhead product from the fractionators Vis treated in a conventional manner, namely condensed, a portion reiiuxed to the fractionators and the remainder yielded from the unit through conduits 22S Vand 250. The bottom streams are combined through

conduits

232 and 254 and introduced through conduit 234 to accumulator 235. From this Vessel the remaining eilluent is passed to the remain ing stage of the lproduct fraction, namely to the decyclohexanizer 264. Before entering this vessel the accumulator material is preheated by passage through heat changer 260 countercurrent to the bottoms from vessel 264 and then through steam heater 262.

The overhead vapors from the decyclohexanizer are condensed and split, with a portion being returned to the decyclohexanizer as reflux and the remainder being yielded as cyclo- Yhexane product through conduit 276. The remain portion of the reaction effluent is Withdrawn from ing the bottom of decyclohexanizer, cooled in exchanger 280 and yielded from the unit for use as motor fuel.

The following example is provided in illustration an application of a preferred embodiment of the invention on a commercial scale.

EXAMPLE Feed preparation Flows Gal. /day Feed to denormalhexanizer (1) 238.460

Composition- Volume percent Isohexanes 0.` n-Hexaue Methylcyclopentane Isoheptanes Benzene Cyclohexane 1-1, d1methy1cyc1opentane(+) Denormalhexanizer overhead (17) Composition- Isohexanes Methylcyclopentane n-Hexane Isoheptanes Benzene Cyclohexane Denormalhexanizer bottoms (23) Temperatures Top bottom I Benzenev hydragenaton Flows Y Gal. /day Hydrocarbon feed to reactors (.2) 259,000

Composition- Volume percent n-Hexane 58.

5 Methylcyclopentane 22.7 Benzene 2.8 Cyclohexane 1.8 Isohexanes 13.9 lsoheptanes 0.3

Hydrogen feed (plus recycle) (S6 and 37) 9,810

Composition- 10 Hydrogen mols/day 6252 Light palans lume percent 75.2 n-Hexane do 15.5 Methylcyclopentane do 2.8 Cyclohexane do .11 Isohexanes d0 6.1

Feed to hydrogen stripper (42) 264,160

Composition- Volume percent Light parans 1.4 n-HeXane 57.3 Methyleyclopentane 22.2 Cyclohexane 5.2 Isohexanes 13.6 Isoheptanes 0.3

Catalyst-hydrated nickel oxide-108,000 lbs. in each reactor.

Temperatures: F. Reactor feed (12) 380 Reactor efliuent (24) 470 High temperature separator (28) 200 Gas `scrubber (34) 105 Hydrogen stripper (44)- 25 Top 220 Bottom 325 Pressures p.s.i.g. Reactor (18) 410 High temperature separator (28) 400 Gas scrubber (34. 395 Hydrogen stripper (44) 130 30 Lsomerization unfit Flows Gal. /day Hydrocarbon feed to reactor (80, 228 and 250) 416,200

Composition- Volume percent n-Hexane 63.1 Methylcyclopentane Cyclohexane Isohexanes Isoheptanes Alma-complex catalyst to reactor (80 and 90) 299,830 HC1 (recycle) to reactor (116) 19.700 Reactor efHuene (84) 736,080

Composition- 4:0 n-Hexane 16.1 Methylcyclopentane 2.3 Cyclohexane 9.6 Isohexanes 28.0 Catalyst 40.9 HC1 2.7 Isoheptanes 0.1

1-1, dimethylcyclopentane(+) 0.3

Temperatures: F. Hydrocarbon reactor feed (80) 80 Reactoreuent (84) 140 HC1 stripper (114)- Top Bottom Pressures:

Reactor (82) Coalescers (98 and 98a) HCl stripper (bottom) (114) Sand towers (150 and 150s.) 153 Product fractionation Flows: Gal./day Feed to Deisohexanizers (158) 413,340

Composition- Volume percen n-Hexane 28.5 Methylcyclopentane 4.1 Cyclohexane 17.1 Isohexanes 49.6 Isoheptanes 0.2 1-1, dimethylcyc1opentane(|) 0.5 Deisohexanizer (166) overhead (178) 108,720

Compositionn-Hexane 8.9 Isohexanes 90.8 Methylcyclopentane 0.2 55 lCyclohexane 0.1

Desohexanizer (190) overhead (.202) 129,320

Compositionn-Hexane 23.9 Isohexane 75.6 Methylcyclopentane 0.4 Cyclohexane 0.1

Feed to demethylcyclopentanizer (210) 175,300

Compositionn-Hexane 44.1 Metnylcyclopen n 9.3 Cyclohexane 40.2 Isohexanes 4.8

Isoheptanes 0.5

Product fractionation-Continued lows: GaL/day Demethylcyclopentanizer overheadV (to isomerizanon unit) (22s and 25o) 108,400 Compositionn-Hexane 71.3 Methylcyclopentane 15.0 Isohexanes 7.8 Cyclohexane 5.7 Isoheptanes 0.2 Feed to decyclohexanzer (258) 66,910

v Composition- Cyclohexane 6.0 Methylcyclopentane 0.1 Isoheptanes 1.0 1-1, dimethy1cyclopentane(+) 2.9 Cyclohexane product (276) 65,160

Compositionyclohexane 98.1 Isoheptanes `1.0 Methylcyclopentane 0.1 1-1, dimethylcyclopentane(+) 0.8 Decyclohexanizer bottoms -to motor fuel (278) 1,770

Composition- 'Cyclohexane 20.7 1-1, d1methylcyclopentane(+) 79,3 Temperatures: F. Feed to deisohexanzer (158) 240 Deisohexanizer (166)- OD 200 Bottom 248 Deisohexanizer (190)- To 205 Bottom 255 Demethylcyclopentanizers (216 and 238)- Top 225 Bottom Decyclohexanizer (264)- Top Bottom Presentes:

Deisohexanlzer 166) Deisohexanizer 190) Demethylcyclopentanizers (216 and 238 Decyclohexam'zer (264) Having thus described the invention by providing a specific example thereof, it is to be understood that no undue limitations or restrictions are to be drawn by reason thereof, and that many variations and modifications are within the scope of the invention.

We claim:

1. A process for the isomerization of hydrocarbons which comprises contacting a hydrocarbon feed comprising normal hexane and methylcyclopentane in a reaction zone with an aluminum chloride-hydrocarbon complex catalyst and hydrogen chloride at a temperature of be-.

tweenabout 90 F. and about 160 F. whereby the feed material is isomerized, introducing the reaction zone efliuent to a settling zone wherein separation between hydrocarbons and catalyst is eifected, recycling at least a portion of the catalyst to the reaction zone, passing the hydrocarbon phase from the settling zone to a coalescing zone wherein the removal of additional catalyst is effected by contacting with a catalyst coalescing medium selected from the group consisting of sand, charcoal, and bauxite, venting the hydrocarbon effluent from the coalescing zone to effect removal of light hydrocarbon gases, contacting the vented gases with absorbent obtained as hereinafter described whereby entrained `hydrogen chloride is absorbed from said gases, combining absorbent and absorbed hydrogen chloride with the remaining liquid portion of the coalescing zone hydrocarbon efliuent, passing the combined material to a hydrogen chloride stripping zone wherein the major portion of the hydrogen chloride is separated, removing and recycling stripped hydrogen chloride to the reaction zone, utilizing a portion of the stripped hydrocarbon material as said absorbent, passing the remainder of the stripped hydrocarbon through a caustic wash for the neutralization of any remaining hydrogen chloride, passing the caustic washed material through a sand tower for the removal of entraned caustic, then introducing said effluent to a series of fractionation zones wherein various components of said eiuent are separated and recycling unreacted methylcyclopentane and normal hexane to the reaction zone.

2. A process for the isomerization of hydrocarbons which comprises contacting a hydrocarbon feed comprising normal hexane and methylcyclopentane and containvnickel oxide hydrogenation catalyst in the presence of hydrogen at a temperature between about 300 F. and about 450 F. in a hydrogenation zone whereby the benzene in the feed material is hydrogenated to cyclohexane and the sulfur reacts with the nickel catalyst to form nickel sulfide, introducing the hydrogenation reaction zone eluent into a separation zone from which a gaseous materia-l rich in hydrogen is vented, passing the vented material through a cooling zone and into a gas scrubbing zone for the separation of liquid and gas rich in hydrogen, returning the liquid from the scrubbing zone to the separation zone and the hydrogen-rich gas to the hydrogenation zone, introducing said combined liquids to a stripping zone wherein the remaining hydrogen is removed, said hydrogen also being recycled to the hydrogenation zone, passing the liquid from the stripping zone to an isomerization zone wherein this material is contacted with an aluminum chloride-hydrocarbon complex catalyst and hydrogen chloride at a temperature of between about F. and about 160 F. whereby the feed material is isomerized, introducing the isomerization zone efduent to a settling zone wherein separation between hydrocarbons and catalyst is effected, recycling at least a portion of the catalyst to the isomerization zone, passing the hydrocarbon phase from the settling zone to a coalescing zone wherein the removal of additional catalyst is eifected, venting the effluent from the coalescing zone to effect removal of light hydrocarbon gases, contacting the vented gases with an absorbent obtained as hereinafter described, whereby hydrogen chloride is absorbed fro-m said gases, combining the absorbent and absorbed hydrogen chloride with the liquid portion of the coalescing eiuent, passing the combined material to a hydrogen chloride stripping zone wherein the major portion of the hydrogen chloride is separated, removing and recycling stripped hydrogen chloride to the isomerization zone, utilizing a portion of the stripped hydrocarbon material as said absorbent, passing the remainder of the stripped hydrocarbon through a caustic wash for the neutralization of any remaining hydrogen chloride, passing the caustic-washed material through a sand tower for the removal of entrained caustic, then introducing said eflluent to a series of fractionation zones wherein various cornponents of said eluent are separated, and recycling unreacted methylcyclopentane and normal hexane to the reaction zone.

3. The process of claim 2 in which the isomerization eiuent is divided into two portions, the iirst portion is fractionated to provide a product comprising essentially isohexanes, the second portion is fractionated to provide a product comprising essentially isohexanes and normal hexane, and the remainders of the two portions are cornbined and introduced to a series of fractionation zones wherein methylcyclopentane and cyclohexane are successively removed therefrom.

4. In a process for the isomerization of hydrocarbons which comprises contacting a hydrocarbon feed comprising an isomerizable hydrocarbon selected from the group consisting of isomerizable normal parafiins and naphthenes with an aluminum halide-hydrocarbon complex catalyst promoted by hydrogen halide, thereby isomerizing said hydrocarbon, and removing said catalyst from admixture with the thus treated hydrocarbon product, the improvement which comprises passing thus treated hydrocarbon product to a gas removal zone in which gaseous material is separated from the liquid hydrocarbon product and vented from the system, contacting the vented gases with an absorbent obtained as hereinafter described and thus effecting the absorption of hydrogen halide in said vent gas by said absorbent, mixing the resulting absorbent containing hydrogen halide with said liquid hydrocarbon product, passing the rulting mixture to a hydrogen halide stripping zone wherein hydrogen halide is removed from said hydrocarbon product by stripping, and

returning part of the thus stripped hydrocarbon product to contact with said vented gas as hereinbefore described.

5. In a process for the isomerizationv of hydrocarbons which comprises contacting a hydrocarbon feed comprising normal hexane and methylcyclopentane With an aluminum chloride-hydrocarbon complex catalyst promoted by hydrogen chloride, thereby isomerizing said hydrocarbons, and removing most of said catalyst from admixture with the thus treated hydrocarbon mixture, the improvement which comprises passing thus puried hy- `drocarbon product to a coallescing zone wherein said hydrocarbon product is contacted `with a catalyst coalescing medium selected from the group consisting of sand, charcoal, and bauxite and remaining traces of catalyst are coalesced and removed, passing thus treated hydrocarbon product to a gas removal zone in which gaseous material is separated from the liquid hydrocarbon prod uct and vented from the system, contacting the vented gases With an absorbent obtained `as hereinafter described and rthus efecting the absorption of hydrogen chloride in said vent gas by said absorbent, mixing the resulting absorbent containing hydrogen chloride with said liquid hydrocarbon product, passing the resulting mixture to a hydrogen chloride stripping zone wherein hydrogen chloride is removed from said hydrocarbon product by stripping, returning part of the thus stripped hydrocarbon product to contact with said vented gas as hereirbefore described, and recovering isomerized hydrocarbons from 10 the remainder of said ,hydrocarbon product.

References Cited in the tile of this patent UNITED STATES PATENTS I5 2,303,075 Frey n Nov.v2"4, 1942 2,379,550 Sutton et al July 3, 1945 2,381,439 Douville et a1. Aug. 7, 1945 2,420,883 Johnson et al. May 20, 1947 2,755,317 Kassel July 17, 1956

Claims

4. IN A PROCESS FOR THE ISOMERIZATION OF HYDROCARBONS WHICH COMPRISES CONTACTING A HYDROCARBON FEED COMPRISING AN ISOMERIZABLE HYDROCARBON SELECTED FROM THE GROUP CONSISTING OF ISOMERIZABLE NORMAL PARRAFINS AND NAPHTHENES WITH AN ALUMINUM HALIDE-HYDROCARBON COMPLEX CATALYST PROMOTED BY HYDROGEN HALIDE, THEREBY ISOMERIZING SAID HYDROCARBON, AND REMOVING SAID CATALYST FROM ADMIXTURE WITH THE THUS TREATED HYDROCARBON PRODUCT, THE IMPROVEMENT WHICH COMPRISES PASSING THUS TREATED HYDROCARBON PRODUCT TO A GAS REMOVAL ZONE IN WHICH GASEOUS MATERIAL IS SEPARATED FROM THE LIQUID HYDROCARBON PRODUCT AND VENTED FROM THE SYSTEM, CONTACTING THE VENTED GASES WITH AN ABSORBENT OBTAINED AS HEREINAFTER DESCRIBED AND THUS EFFECTING THE ABSORPTION OF HYDROGEN HALIDE IN SAID VENT GAS BY SAID ABSORBENT, MIXING THE RESULTING ABSORBENT CONTAINING HYDROGEN HALIDE WITH SAID LIQUID HYDROCARBON PRODUCT, PASSING THE RESULTING MIXTURE TO A HYDROGEN HALIDE STRIPPING ZONE WHEREIN HYDROGEN HALIDE IS REMOVED FROM SAID HYDROCARBON PRODUCT BY STRIPPING, AND RETURNING PART OF THE THUS STRIPPED HYDROCARBON PRODUCT TO CONTACT WITH SAID VENTED GAS AS HEREINBEFORE DESCRIBED.