US2388510A - Olefin conversion - Google Patents

Description

Nov.. 6, 1945. H. H. VGE

- OLEFIN coNvERs 10N Fired Aug. 141, 19,42

Patented Nov. 6, 19.45

y :,ssssm onsrm coNvsasroN Hervey H. Voie, Berkeley, Calif.. assigner to Shell Development Company, San Francisco, Calif., a corporation of Delaware Application Amst 14. raiz. serial No. 454369 l 11 claims. (ci. 26o-essa) This invention relatesto the production of normal butylenes and relates more particularly to an improved process for the production of 2- butylene from hydrocarbon mixtures comprisin 1butylene and/or isobutylene. .A

Normal butylenes are finding application as starting materials in the production of an ever increasing number of vitally important derivative products. Often the emcient production of many of these products is dependent upon the availability of a substantially pure 2butylene feed. However, themore readily available sources of butylene such as the butylene-containing hydrocarbon tractionsobtained, for example, by treatments such as distillation and thermal or catalytic conversions of naturally occurring petroleum, natural gas, natural gasoline, distillate petroleum rennery products, and various other carbonaceous materials, generally furnish the normal and branched chain butylenes iu admix.-

-ture with one another. 2butylene in either or both of its isomeric forms, cis-2butylene and trans-2butylene, can be separated economically from hydrocarbon fractions comprising l-butylplexity, 4cost of operation, or inability to eifect conversions to the .desired normal butylene isomer in the absence of substantial butylene polymerization or degradation. As a result processes which can utilize only the 2butylene, as well as even those processes which can usev both of the normal butylene isomers, as starting material are generally constrained to use only the 2butylene content of the more readily available butene-containing hydrocarbon fractions. A process enabling the more eillcient production of substantially pure normal butylene, particularly substantially pure 2butylene, from hydrocarbon fractions comprising a mixture oi' normal butylenes and isobutylene. in the absence of substantial polymerization' reactions is therefore greatly desired.

Itis'an-obiect of the present invention to prof vide an improved process'for the more eiiicient production of 2butylene from hydrocarbon mixtures comprising 1butylene and iso-butylene.

Another object of the invention is to provide an improved process for the more eilicient conversion of 1butylene to 2butylene.

A further. object of the invention is to provide an improved process for the more eillcieut conversion of isobutylene' to normal butylenes, more particularly to 2butylene. Other objects and advantages of the invention will be apparent from the following description thereof.

In' accordance with the invention, a hydrocarbon mixture from any suitable source comprising, for example, satupted and unsaturated hydrocarbons having f r carbon atoms to the molecule is fractionate in a feed fractionating zone to separate a vapor fraction comprising 1butylene, isobutylene and isobutane from a liquid fraction comprising 2butylene and any normal butane present. Thevapor fraction is contacted in a first conversion zone with a catalyst and under well'deilned conditions which, it has-been found. enable the eillcient conversion of 1butylene to 2butylene in the absence oiv any substantial hydrocarbon polymerization or decomposition. Resulting '2butylene is separated from the emuence of the first conversion zone as a nal product and the remaining hydrocarbons comprising isobutylene are contacted in a second conversion zone with a catalyst and at well denned conditions which, it has been found, effect the eilicient conversion of isobutylene to normal butylenes. 2-

butylene is separated from the emuence of the second conversion zone as a iinal product and the remaining hydrocarbons comprising 1butylene are passed to the first conversion zone. In one embodiment of the invention the accumulation within the system of isobutane, if present in the charge, is avoided by continuously or intermittently subjecting at least a part of the hydro- Y carbon stream passing from the first to the second conversion zone, to a. treatment effecting the separation of at least a substantial amount of the paramn hydrocarbons therefrom.

In order that the invention will be more readily understood, it will be described vin detail with reference to the attached drawing forming a part of this speciilcation and illustrating, more or less diagrammatically, onel form of apparatus suitable ior executing the invention.

A butylene-containing hydrocarbon mixture such' as. lfor example, a butane-butylene fraction separated by fractionation from-the products of a thermal or catalytic hydrocarbonconversion.

process, is drawn from an outside source and forced by means of pump Il through valved line II into a feed fractionating zone. The feed fractionating zone may comprise., for example, a

fractionator I2. The use of solvent extraction or l Within fractionator I2 a vapor fraction comprising l-butylene, isobutylene and any isobutane present` is separated from a liquid fraction comprising 2- butylene and any normal butane present. The liquid fraction is withdrawn from fractionator I2-throughvvalved line I3 and may be subjected to asubsequent treatment, by means not shown in the drawing, which may comprise.' for example, solvent extraction .or solvent distillation to eiect the separation of 2-butylene from any normal butane admixed therewith. The vapor fraction is passed .from fractionator I2 through line I4 and a cooling means, for example, condenser I5, into an accumulator I8.

From accumulator I6 the hydrocarbons are forced by means of pump i8 through valved line I! into a heating zone. A part of this stream is diverted-through valved line as reflux to fractionator I2. Cooling means not shown in the drawing may be provided to cool the reilux stream. An indirect heat exchanger- 22 is provided in line,l9 to permit preheatingv of the stream by means of indirect heat exchange, for example, with a side-stream obtained within the system. The heating zone may comprise a furnace structure 23 containing an externally 'heated coil 24. Within coil 2,4 the hydrocarbon stream is heated to a temperature sumciently high vto maintain the desired temperature within the subsequent first A conversion 'zone.- The suitable catalyst material capable of catalyzing l the conversion of l-butylene to 2-butylene. Though'some' conversion to the desired isomer can be obtained with several catalysts comprising aluminum oxide under certain conditions, it is essential to the'attainment of the degree of operating eiilciency enabling production. of 2-butylene on a practical scale that substantially equilibrium conversion of l-butylene to 2-butylene is obtainedin the absence of any substantial polymerization or degradation of normal butyl- 'en es or isobutylene. The catalyst must in addiing one or several of such steps as heating at elevated temperatures, for example. in the range of from about 500 C. to about 800 C., and treat-l ment with steam or acid. A preferred catalyst comprises thel activated bauxite sold lby The Porocel Corporation under the trade-name PoroceL A temperature in the range of from about 275C. to'about 400 C. and preferably between about 300 C. and 375 C. is maintained within reaction chamber 26. The conversion is eifected at atmospheric pressure, although slightly elevated pressures, for example, up to about 100 lbs. and higher may be used if desired. The rate o! i'low through reaction chamber 2Q is s,see,e1o v carefully Acontrolled to maintain a 'velocity of v ow therethrough which in terms 0i liquid hourly space velocity will be in excess of about 5 and up to as -high as, for example,4 about 150, and v preferably between about l0 and 25. By the term liquid hourly space velocity ss used throughout-the specification and claims 'is meant the total lamount of charge entering the reactor.

measured in the liquid state, per unit volume of catalyst, per hour. Reduction of temperature subnantially below the above-defined limit necessitates considerably reducing the throughput rate to obtain the desired high conversion to 2-butylene. Further, lowering both the temxerature and flow velocity below the prescribed conditions causes a loss of a substantial amount of valuable butylenes due to polymerization reinvention, is illustrated by the following ex-l amples:

Emmple I I-butylene was passed over activated bauxite, at atmosuheric pressure and at the temperature and liquid hourly space velocities indicated in the following table. The amount of 2butylene produced is given as percentage by weight of the product obtained :A

Tulip. L. n. s. v. mylene The formation of materiel bisher mung uan C4 hydrocarbons was too slight to be apparent.

Emmple I A butane-butene hydrocarbon fraction. the composition of which is given in weight percent 5o in column A of the following table. wss passed over activated bauxite at 350 C. at a liquid hourly space velocity oi' 36 and at s pressure of 6 atmospheres. The composition of the products obtained after a three-hour period of operation is shown in weight percent in column B of the following table:

The emciency with which substantially selective conversion of 1butylene to S-butylene can bel effected in accordance with the invention, when treating a. mixture ot hydrocarbons containing both saturated and unsaturated hydrocarbons having four carbon stoms tothe molecule is clearly shown by the above example. y

Decreasing the ilow rete below the aboveprescrlbed range to a substantial degree, even thoughapermissibleoperstingteniperahinis maintainedcausesoleilnpolymerilationtotake asa'aeio place as a prominent reaction with a concomitant reduction in the amount of the desired Z-butylen'e, produced, asl illustrated by the following example. l

Erample III l-butylene was passed over activated bauxite at a temperature of 315 C. andV atmospheric pressure with a liquid hourlyspace velocity of 9. A conversion of -1-butylene to 2-butylene of 41.2% was obtained while the formation oi' material heavier than C4 hydrocarbon was toofsmali to be readily determined. A second experiment was conducted4 at substantially identical conditions with the exception that the liquid hourly space velocity was reduced to 3. Under the latter conditions, the reaction product consisted of 14.5% by weight of material heavier than C4 hydrocarbons; t

Effluence from reaction chamber 26 comprising Z-butylene, isobutylene, some unconverted l-butylene, and isobutane, is passed through line 21 and a suitable cooling means, for example, a heat exchanger 28, into a fractionating zone. The fractionating zone' may comprise a iractionator 29. Within fractionator 29 a liquid fraction comprising 2-butylene is separated fromV a vapor fraction comprising isobutylene, 1-buty iene and isobutane. The liquid fraction is removed from fractionator 29 through valved line 30 and eliminated from the system as a final product. The vapor fraction is removed from fractionator 29 and passed through line 3I,'and.

a cooling means, for example `a condenser 32, into an accumulator 33. A part of the stream passing through line 3| may be recycled through iine by means of pump 36 into line I9.

If a .charge consisting essentially only of 1- -butylene is to be converted to 2butylene, it may be introduced directly into line i9 from an outside source by means of valved line 31. Such charge may constitute at least a substantial part of the charge to the system.

The products within accumulator 33 are withdrawn therefrom through valved line 39 and a part thereof may, if desired, be eliminated from the system. A part of the stream flowing through line 39 is passed through valved line 40 as a reflux to fractionator 29. In the preferred embodiment of the invention the hydrocarbon stream comprising isobutylene, l-butylene, and isobutane not diverted through line 40, is forced by means 'of pump 4I through valved lines 39 and 42 into a heating zone. Line 42 is provided with a preheating means which may comprise an indirect 'heat exchanger 43. The heating zone may comprise a suitable furnace structure 44 housing an externally-heated coil 45. Within coil 45 the hydrocarbon stream is heated to a temperature sufficiently high to maintain the desired temperature conditions within a subsequent second conversion zone. From coil 45 the hydrocarbon stream is passed through line 46 vinto a second conversion zone.

The second conversion zone may comprise an enlarged reaction chamber 41. Within reaction chamber 41 the hydrocarbon stream is contacted with a catalyst material capable of catalyzing the conversion of isobutylene to normal butylenes. Though various catalyst materials have been pro'- posed heretofore for conversion of normal butylenes to branched chain butylenes, such as for example the permutites, the activity of these catalysts is often not sutllciently pronounced to enable their satisfactory use in a practical scale conversion 'of isobutylene to normal butylenes. These catalysts have been found, furthermore, vto possess an undesirable tendency to catalyze the saturation of the olefinic charge. An added disadvantage of these catalysts resides in their inability to undergo frequent regenerations without substantial detrimental effect to their usefulness. It has now been found that certain activated aluminas are decidedly more active and permit the attainment of considerably longer operating periods. Activated bauxite, though highly advantageous for the conversion of 1butylene to 2-butylene, is, however, considerably less emcient in its ability to catalyze the conversion of isobutylene to normal butylenes than activated alumina. In the preferred method of carrying out the invention, an activated alumina, and preferably an acid-washed activated alumina, is utilized as the catalyst within reaction chamber 41. The use of higher temperatures and lower space velocities than those prescribed for the iconversion of 1'butylene to 2-butylene are necessary for the eiiicient conversion of isobutylene to normal butylenes. It has been found that a temperature within the range of from about 400 C. to about 600 C., and preferably from about 450 C. to about 550 1 C., and a liquid hourly space velocity in the range of from about 1 to about 15, and preferably not substantially in excess of about l0, substantially equilibrium conversions of isobutylene to normal butylenes are obtained in the absence of substantial polymerization or degradation reactions. Atmospheric` or superatmospheric pressure up to, for example, about lbs., or higher, may be maintained within reaction chamber 41. The efiiciency with which isobutylene is converted to normal butylene under thes conditions is evidenced by the following example.`

Example IV formation of normally liquid products was evidenced during the operation.

Efiiuence from reaction chamber 41 is passedv through valved line 48 equipped with suitable cooling means, such as, for example, an indirect heat exchanger 49, into a fractionating zone. Tlf'e fractionating zone may comprise a fractionator 50. Within fractionator 50 a liquid fraction comprising Z-butylene is separated from a vapor fraction comprising l-butylene, some unconverted isobutylene and isobutane. i The liquid fraction is withdrawn from fractionator 50 through valved line 5| and eliminated from the system as a final product. 'I'he vapor 'fraction is withdrawn overhead from fractionator 50 and passedv through line 52, and a suitable cooling means, for example, a condenser 53 into accumulator 60. A part of the hydrocarbon stream flowing through line- 52 .may be recycled by means of pump 56 through line 51 into line 42.

If it is desired toconvert a hydrocarbon stream consisting essentially of isobutylene to normal butylenes, this may be charged to the system through valved line 59 leading into line 42. Such an isobutylene stream may comprise at least a substantial part of the charge to the system.

rmduea emulated-within eeeuniuietor n are withdrawn therefrom through valved line Il and a part thereof may, it desired, be removed ,u

from the system as a nnal product. A part o! the hydrocarbon' stream iiowing through line i is passed through valved line 62 as reilux to fractlonator Il. In the preferred embodiment of the invention substantially all ofthe hydrocarbons withdrawn from accumulator il. not diverted through line 62, are forced by means of pump I3 through valved lines Il and Il vinto line il to be admixed therein with the charge toV thc ilrst conversion zone. The l-butylenes produced within reaction chamber 41 are thereby returned to the ilrst conversion zone to be converted-therein to 2butylene.

Ii' normal butane is present to any substantial duree inthe eiliuence of reactiony chamber 41. the hydrocarbon stream may be diverted from line Il through valved line II-into' i'eed iractioiator l2.

Isobutane when present in the charge to th system is eliminated therefrom with a minimum ly removing at least a part oi.' the hydrocarbon stream from line l through valved line 01 into a solvent extraction zone, comprising. for example, an extraction column tl. Within column ll the hydrocarbon stream is contacted countercurrently with a suitable solvent such as, for example, a mixture oi acetone and water, or any other solvent capable of selectively absorbing oleiins, introduced into the extraction column by means of valved line It. Unabsorbed isobutane is eliminated overhead from column Il through valved line 1l. The solvent containing the absorbed oleiins is withdrawn from column il and forced by means oi pump 11 through line 'Il into a disthrough line l1 is controlled so as to eect the removal o! isobutane from the system through line 1l at a ,rate substantially equal tothat at which this saturated hydrocarbon is introduced that the invention is not necessarily limited to this particular method oi' isobutane removal, and, if desired, the isobutane may be removed at other points within the system, tor example, by solvent 'extracting the hydrocarbon stream flowing itirgough line i4, by means not shown in the drawwiiiie the invention has been described in e .v detailed manner and examples provided illustrating suitable" modes of its execution, it is to be understood that modifications may be made withloss of butylenes by continuously or intermittent- A into the system. It is to be understood, however,

s,sss,sio

lation steps may,'ii desired, be provided to aid any drocarbons within the system. Iclaimasmyinvention: 1. The process for the conversion of l-butyiene to 2butylene in the absence oi any substantial olefin polymerization which comprises contacting l-butylene with bauxite at a temperature of from about 300 C. to about 375 C. and at a liquid or all of the steps electing the separation o( lhyhourly space velocity of from about 10 to about 2'5, said bauxite having nm been subjected to a temperature oi' from about 500 C. to about 800 C. thereby rendering said bauxite active for the conversion o! l-butylene to 2butylene in'said con-- version temperature range. 2. The process for the conversion of Ii-butylene to 2butylenein the absence ot any substantial olefin polymerization which comprises contacting 1-butylene with bauxite .at a temperature o! from about"275 C. to about 400 C. and at a liquid hourly space velocity ot from about 5 to about 150, said bauxite having first been subjected to a temperature of from about 500 C. to about 800' C. thereby rendering said bauxite active for the conversion oi l-butylene to 2butylene in saici of from about 275 C. to about 400 C. and at a liquid hourly space velocity of from about l0 to about 25, thereby effecting the conversion of lbutylene to 2butylene as the predominant reaction, said bauxite having nrst been subjected to a temperaturen! from about 500 C. to about 800 C. thereby rendering said bauxite active for the conversion of 1-butylenel to 2butylene in said conversion temperature range.

4. The process for the production of 2butylene in the absence of any substantial oleiin polymerization which comprises contacting a l-butylenecontaining hydrocarbon mixture consisting essentially of saturated and unsaturated hydrocarbons, havingiour carbon atoms te the molecule, with a catalyst comprising bauxite at a temperature of from about 275 C. to about 400 C. and at a liquid hourly space velocity ot from about 5 to. about 150, thereby eecting the conversion of l-butylene to 2butylene as the predominant reaction, said bauxite having tlr'st been subjected to a temperature of from about 500 C. to about 800 C. thereby rendering said bauxite active for the conversion of 1-butylene to 2butylene in said conversion temperature range.

5.. A process for the production ofZ-butylene from a hydrocarbon mixture comprising l-butylene and isobutylene, which comprises contacting in thescope oi the invention. Thus, for example,

though in the drawing single enlarged reaction chambers are shown as constituting the converl sion zones, it is to be understood that a plurality oi.' such chambers connected in series or in parallel, and/or tubular catalyst-containing reactors, as well as suitable additional means for maintaining desired operating temperatures therein, may

said hydrocarbon mixture in -a first conversionl zone with a catalyst comprising bauxite at a temperature ot from about 300 C. to about 375 C. and at a liquid hourly space velocity oi.' from about 10 to about 25. thereby eiiecting the conversion oi' l-butylene to 2butylene as the predominant reaction, said bauxite having iirst been subjected to a temperature o! from about 500 C. 'to about 800 C. thereby rendering said bauxite active for the conversion of l-butylene to 2butylene in said conversion temperature range, separating a fraction comprising 2butylene and a fraction comprising isobutylene from theeiliuence of the nrst conversion zone. contacting said traction comprising isoassasio butylene in a second conversion sone with a catalyst comprising alumina at a temperature of from about 450 C. to about 550 C. and at a liquid hourly space velocity of trom about 1 to about 10, thereby electing the conversion oi isobutylene to normal butylenes as the predominant reaction,

separating a fraction comprising 2butylene and a traction comprising l-butylene from the eilluf v-euce oi said second conversion zone, and passing said fraction comprising 1butylene tothe nit conversion lone. 4

6. A process for the production of 2butylene from a hydrocarbon mixture comprising 1-buty1- ene'and isobutylene, which comprises contacting said hydrocarbon mixture in a nrst conversion zone with a catalyst comprising bauxite at a temsecond conversion zone, and passing said fraction comprising l-butylene to the iirst conversion zone.

perature of from about 275 C. to about 400 C.

a temperature of from about 400 C. to about 600 C. and at a liquid hourly space velocity of from about 1 to about 15, thereby effecting the conversion o! isobutylene to normal butylenes as the predominant reaction, separating a fraction comprising 2-butylene and a fraction comprising 1-butylene from the eiiiuence oi said secondconversion zone, and passing said fraction comprising l-butylene to the rst conversion zone.

l 7. A process for the production of 2butylene trom a hydrocarbon mixture comprising 1-butylene and isobutylene. which comprises contacting said hydrocarbon mixture in a first conversion zone with a catalyst comprising bauxite at a temperature o! from about v275 C. to about 400 C. and at a liquid hourly space velocity of from about 5 to about 150, thereby eiecting the conversion oi l-butylene to 2butylene as the predominant reaction, said bauxite having rst been subjected to a temperature oi' from about 500` C. to about 800 C. thereby rendering said bauxite active for the conversion oi 1-butylene to 2butylene in said conversion temperature range, separating a traction comprising 2butylene and a traction comprising isobutylene from the eiiluence of the iirst conversion zone. contacting said fraction comprising isobutylene in a second conversion zone with a catalyst comprising alumina at a temperature oi from about 400 C. to about 600 C. and at a liquid hourly space velocity of from abouti to about 10, thereby effecting the conversion of isobutylene to normal butylenes as the predominant reaction, separating a fraction comprising 2butylene and a fraction comprising 1butylene from the eiiiuence of said second conversion sone, and passing vsaid fraction comprising Il-butylene to the nrst conversion zone.

8. A procesadorl the production oi 2butylene from a hydrocarbon mixture comprising 1butyl ene and isobutylene; which comprises contacting said hydrocarbon mixture in a first conversion :one with a st comprising bauxite at conditions en the conversion of 1-butylene to 2butylene as 'the predominant reaction; said bauxite havinglnrst been subjected to a temperature of from about 500 C. to about 800 C. thereby rendering said bauxite 'active for the conversion of l-butylene to 2butylene in said conversion temperature range, separating a fraction comprising 2butylene and a fraction comprising isobutylene from the eiiluence of the iirst conversion zone, contacting saidfraction comprising isobutylene in a second conversion zone with a catalyst comprising alumina at conditions effecting the conversion of isobutylene to normal butylenes as the predominant reaction, separating a fraction comprising 2butylene and a fraction comprising 1-buty1ene from the eiiluence of said 9. The process for the production of 2butylene `from a hydrocarbon mixture comprising 1buty1 ene and isobutylene in admixture with 2butylene, normal butane and isobutane, which comprises separating a fraction comprising l-butylene, isobutylene, and isobutane from said hydrocarbon mixture, contacting ,said fraction in a iirst conversion zone with a catalyst comprising bauxite at a temperature of from about 275 C. to about 400 C. and at a liquid'hourly space velocity of from about 5 to about 150, thereby effecting the conversion of l-butylene to 2butylene as the predominant reaction, said bauxite having first been subjected to a. temperature of from about 500 C. to about 800 C. thereby rendering. said bauxite active for the conversion of l-butyiene to 2butylene in said conversion temperature range, separating a. fraction comprising 2butylene, and a fraction comprising isobutane from the eiiiuenc'e of the rst conversion zone, contacting the remaining eiiluence of the rst conversion zone Vcomprising isobutylene in a second conversion zone with a catalyst comprising alumina at a temperature of from about 400 C. to about 600 C. and at a liquid hourly space velocity of -from about 1 to about 10, thereby converting isobutylene to normal butylenes asA the predominant reaction, separating a fraction comprising 2butylene and a fraction comprising 1butylene from the eiiiuence of the second conversion zone, and passing said fraction comprising l-butylene to the rst conversion zone.

10. The process for the production o f 2butylene from a hydrocarbon mixture comprising 1- butylene and isobutylene in admixture with 2'- Abutvlene, normal butane and isobutane, which comprises separating a fraction comprising 1- butylene, isobutylene and isobutane from saidhydrocarbon mixture, contacting said fraction in a rst conversion zonel with a catalyst comprismg bauxite under conditions eiecting -the conversion of l-butylene to 2butylene as the predominant reaction, said bauxite having first been subjected to a temperature of from about 500 C. to about 800 C. thereby rendering said bauxite active -for the conversion of l-butylene to 2butylene in said conversion temperature range, separating a fraction comprising 2butylene and a fraction comprising isobutane from the eiiiuence of the first conversion zone, contacting the remaming eiiluence of the first conversion zone comprising isobutylene in a second conversion zone with a. catalyst comprising aluminum oxide under conditions eiecting the conversion of isobutylene said fraction comprising l-ybutylene to the rst conversion zone. 1

ene from a. hydrocarbon mixture comprising 1- butylene and isobutylene in admixture with isolbutane, which comprises contacting said hydrocarbon mixture in a rst conversion zone with a catalyst comprising bauxite under conditions effecting the conversion ot l-butylene to 2-butylene as the predominant reaction, said bauxite having rst been subjected to a temperature of from about 500 C. to about 800 C. thereby rendering said bauxite active for the conversion of 1-butylene to 2-butylene in said conversion-tem-- perature range. separating a traction comprising 2-buty1ene from the eiiiuence of the tix-st conversion zone. separating isobutane fromA the eiiiuence of the nrst conversion concat a rate substantially equal to that at which isobutane it introduced into the nrst conversion lone, contactingthe remainingeiliuenceoithenrstconvenion zone comprising isobutylene in a second conversion zone with a catalyst comprising aluminum oxide under conditions eilecting the conversion or isobutylene to normal butylenea as the'predominant reaction, separating a iraction comprising 2butyiene and a fraction comprising 1but1l l ene from the emuence o! the second conversion zone. and passing said fraction comprising 1bu tylene to the nrst conversion sone.

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