Патент USA US2406868код для вставки
Patented Sept. 3, 1946 2,406,868 UNITED sTaTEsPATENT ornce _ 2,406,868 ' ~ New ISOMERIZATION rnoosss Carl_0. 'vl‘ongberg, _West?eld, and Homer J. Hall. Roselle, N. .L, asslgnors to Standard Oil De velopment Company, a corporation oi’ Delaware No Drawing. Application August 15, 1941, ~ Serial No. 407,008 ' ' ‘7 13 Claims. (Cl. zoo-e835) 1 1 , . 2 , ess employing novel catalyst promoter to accom containing a very small amount of cycle propane or cyclo butane or their alkyl derivatives such as methylcyclopropane, dimethylcyclopropane, branched chain para?lns. with aluminum chloride and one of the conven This invention relates to the isomerization of paramnic hydrocarbons by means of a novel proc ethylcyclopropane', methylcyclobutane, dimethyl plish the production of iso- or branched'chain para?ins from either straight chain or less‘ 5 cyclobutane and ethylcyclobutane is isomerized _ - The preferred process resides in the isomeriza- tional ‘promoters, the activity of the catalyst is tion of normal para?lns to isop'ara?ins using at materially increased over and above that which least one aluminum halide as the catalyst with would ordinarily be expected in the absence of or without the‘ presence of the usual promoters 10 such naphthenes or \cyclo aliphatic hydrocarbons.‘ The exact nature of the. mechanism of the reac therefor. These promoters may be free halogens, tion which results in the increased life of the cat for example chlorine or bromine, the hydrogen _ alyst is not de?nitely known. However, it is halides, for example hydrogen chloride or hydro thought that the naphthenes ortheir degradation gen bromide, the alkyl halides, such as, for ex ample, methyl, ethyl, propyl', butyl,_ amyl, chlo rides or bromides, the alkyl polyhalides, such as, for example, chloroform and carbon tetrachloride, and the like.‘ Water may also be employed as a promoter. It has been customary, in the past, to subject various types of feed stocks predominat ing in straight chain .para?inic hydrocarbons, particularly of the butane and pentane feeds,‘ to isomerization reactions in order to increase the ' 15 products produced in the reaction zone combine in some manner with the aluminum chloride to produce a complex therewith which, in effect, is the real catalyst for the reaction or which acti vates secondarily the aluminum chloride in its 20 isomerizing activity of the normal pentane feed stock. I ' Not only may the reaction be carried out with a feed stock containing the heretofore mentioned naphthenes in small amounts, but as a further available quantities ‘of isobutane and isopentane. However, one of the difficulties encountered in the 25 modi?cation of the invention, once the catalytic isomerization of normal para?lns containing at least 4 carbon atoms per molecule with aluminum chloride, for example, and hydrogen chloride as a promoter, is‘ the fact that catalyst life is not as activity of the fresh aluminum chloride has been enhanced by treatment with the naphthene-con taining feed stock, the feed stock may be changed \ in a continuous process from the naphthene-con great - as desired in commercial operation. It 30 taining feed to one free of naphthenes and com posed essentially of the straight chain para?ln or has been found that in the ordinary commercial of the straight chain para?in admixed with small continuous unit for isomerizing, for example nor amounts of other para?inic hydrocarbons without mal butane to isobutane in the presence of alu the resultant usual loss of catalytic activity of the - minum chloride and hydrogen chloride, that the catalytic activity of the aluminum chloride, al 35 aluminum chloride which has been so treated. 'In other words, once the aluminum chloride has though quite satisfactory at the beginning of its been contacted with a naphthene-containing feed a use, is found to be too rapidly degraded to the stock, its effective catalyst life thereafter has now point where the loss of activity for isomerizing been found to be materially increased even though‘ requires that it be discarded and replaced by the feed stock which is employed thereafter con fresh aluminum chloride. This degradation and tains no naphthenes. ' ' loss of activity was thought to be as a result of As a further embodiment of the invention, it is the building up of contaminants on the surface‘ contemplated to carry out a continuous commer of the catalyst, thereby reducing the effective cial operation in either liquid phase or vapor contact surface of the catalyst and also to the -» building up of undesirable complexes between 45 phase with or without the presence of elemental or free hydrogen ‘wherein the catalyst during its the hydrocarbons and their degradation products with the aluminum chloride. ‘ It now has been discovered that the effective catalyst life of the aluminum chloride can be un expectedly increased in these commercial opera tions if the normal paraf?n feed stock contacted with the freshly introduced aluminum chloride contains‘small amounts of the 3 and 4 carbon atom naphthenes. By so conducting an isomeri- zation reaction, for example if normal pentane entire useful life has alternately contacted there with a feed stock containing normal para?lns of at least 4 carbon atoms per molecule and small 50 amounts of the 3 and 4 carbon atom naphthenes and a naphthene-free para?lnic feed stock con taining at least 4 carbon atoms and predominant ly of straight chain con?guration though not nec ‘ essarily predominating in the same para?ln as 65 contained in the ?rst mentioned feed stock. The " 3 2,406,868 alternate use of these two types of the feed stocks may be so adjusted as to considerably lengthen the catalyst life, and to thereby effectuate an in creased yield of desired isomeric products per pound of aluminum chloride employed in the al 4 feeds as ?eld butane are likewise desirable. Mix tures of one or more of these heretofore men tioned straight chain para?inic hydrocarbons .are likewise useful in the process, and mixtures which contain' substantial amounts of normal parafiins in conjunction with other paraflins are also suit able for use in the present process. As hereto spective feed stocks being contacted with‘ the fore mentioned these materials as produced from catalyts alternately as heretofore described will petroleum may contain C3 or C4 naphthenes. be disclosed in greater detail hereinafter. It has been found that the naphthenes, cyclo 10 These naphthenes can be removed to give a kylation reaction. The periods of time of the re propane and cyclobutane and their alkyl deriv atives are ‘equally e?icacious in the practice of the present invention regardless of their source of supply. Thus, it is possible to employ as a . naphthene-free feed stock by treatment with con centrated sulfuric acid, halosulfonic acids such as ?uoro- or chlorosulfonic acid, fresh or par tially spent AlCla or by hydrogenation. ' feed stock for the process, a substantially pure The amount of napthenes added to the alu acyclic paraf?nic hydrocarbon mixture the con stituents of which predominate in straight chain minum chloride catalyst should preferably be between about 0.10 and about 4% in the ordinary paraf?ns of at least 4 carbon atoms per mole operation of the process. As previously men cule and to intermittently add from extraneous tioned, if a greater concentration of naphthene sources materials comprising substantially pure 20 is present, the catalyst becomes over-active too cyclopropane and/or cyclobutane, or materials quickly and, as a result, causes excessive degra containing predominant para?inic acyclic hydro dation of the norma] paraf?ns undergoing, isom carbons but containing, also, small amounts of erization'. When the catalyst has absorbed a the desired naphthenes. As a further modi?ca quantity of naphthenes su?icient to bring its ac tion of this alternative process, it is possible to operate on a feed stock of, for example, normal butane or normal pentane, and to intermittently, as the activity of the catalyst would indicate, change to a similar hydrocarbon mixture contain tivity to‘ the desired level the addition of naph thenes can be discontinued until such time as the catalyst activity materially decreases when used in the isomerization of a naphthene-free normal para?ln of at least 4 carbon atoms. ing the desired naphthenes. Superatmospheric pressure is customarily em 30 Among the naphthene-containing feed stocks ployed in order to‘maintain a liquid phase oper found in the oil re?ning industry may be men ation, although it is to be distinctly understood tioned the condensation of natural gas to produce that vapor phase operations are likewise con casinghead gasoline which is distilled to yield a templated in connection with the present inven C5 paraf?n cut, followed by the separation of the 35 tion. The superatmospheric pressures may be normal para?ins from the isopara?ins in the C5 imposed su?icientto maintain a liquid phase op cut, and the use of the normal pentane cut as a eration under the reaction conditions obtained, feed stock in the present process. This stock and it may also be desired to'use pressures up ordinarily will contain traces of alkyl derivatives to as high as 1000 ‘lbs/sq. in. when operating in of cyclopropane, cyclobutane, and/or its alkyl de 40 either liquid or vapor phase. These pressures rivatives. This source of the naphthenes may are designed to suppress the tendency toward be employed exclusively as the feed stock for a cracking, the degradation of the hydrocarbons limited time or as a blending or addition agent treated, particularly where the hydrocarbons to the naphthene-free feed stock ordinarily em ployed in the manner heretofore indicated. An other suitable source of supply of feed stocks which are found to contain the desired'naph thenes may be obtained by the distillation of either parafllnic or preferably naphthenic crude treated are of higher molecular weights, for ex . and which contains the desired naphthenes as a ity of the catalyst, thereby resulting in excessive degradation of the feed stock, molecular hydro ample, the hexanes and heptanes and to give increased contact times and throughputs. 'I'he pressures may be obtained partially by the use of the halogen-containing promoters heretofore mentioned, or they may be also attained by the oils to obtain a C5 fraction, followed by the seg 50 introduction of free or molecular hydrogen either regation of the normal pentane from the isopen alone or in conjunction with the halogen-con tane and the use of this normal pentane fraction, taining promoters. To prevent excessive activ feed stock for the reaction. Straight run naph thas with or without small amounts of naph thenes contained therein may also be employed as feed stocks and sources of naphthenes in the present process. Of course, as heretofore mentioned, naphthenes prepared synthetically, or obtained from other gen has been found to be particularly effective. The reaction conditions are those customarily employed when carrying out para?inic isomeri ployed, if desired, in conjunction with feed stocks zation reactions in the presence of aluminum chloride or aluminum bromide. The quantity of catalyst may be varied between about 1 and about 150% by weight based on the para?in maintained in the reaction zone at any one time. which do not contain the requisite amounts of _ In vapor phase operation the amount of catalyst sources in more or less pure form may be em naphthenes. The heretofore mentioned sources may be much higher. Optimum catalyst con of normal pentane which naturally contain the 65 centrations vary depending upon the other re desired naphthenes may be used in varying action conditions maintained. Preferably a amounts and for varied lengths of time, depend ing to a large extent upon the amount of the C: catalyst concentration between about 15. and about 70% by weight is sufficient in liquid phase and/or C4 naphthenes ‘contained therein. operation. Likewise, the amount of promoter When it is desired to operate with a feed stock 70 employed, may vary considerably, for example, substantially free of the heretofore discussed between about.2 and about 24% by weight of naphthenes, the ordinary feeds may be employed. the hydrocarbon present in the reaction zone at Thus, for example, normal butane, normal pen any one time but preferably it is maintained be tane, normal hexane, normal heptane, and the tween about 4 and about‘10%. The tempera higher homologues, may be employed. Such 75 ture of the reaction zone is maintained depend 2,400,808 5", moval from the isomerization reactor or reactors is well known in the art and generally embodies the stripping of the promoter from the reacted erably between about 100 and about 225° F; for mixture followed by the removal of any residual liquid phase operation. In vapor phase opera tion the temperature oflthe reaction zone may be . 5 amounts of aluminum chloride or aluminum chlo ride complex, as the case may be, and the semi maintained at between about 150° F. and about ration of the‘ 'unreacted- portion of the reacted 500° F. preferably between about 275 and about ' mixture-from the isomeric products produced ~ 375° F. These temperatures are customarily in the reaction by convenient means such as, employed with normal butane isomeriz'ation re actions. However, in ‘the case of normal pe'n- 10 for example, fractionation together with the re cycle of the promoter to the isomerizatlon reac tane, a somewhat less drastic temperature con tors with the optional recycle of unreacted re dition is customarily employed. However, in the actants as well. , present case, where it may be desirable to em As one mode of carrying out the invention, a ploy a C5 feed stock when contacting the cata lyst with naphthenes and a C4 feed stock when 15 feed stock of normal pentane with and without " traces of naphthenes will be described. A feed contacting the naphthene activated catalyst with isomerizing reactants, the temperatures ~ stock containing no naphthenes and composed predominantly of normal pentane under a given “ may vary as between the various types of feed set of reaction conditions with aluminum chlo stocks so as to maintain optimum reaction con ditions for each type of feed stock. On the other 20 ride and promoter will give a 50% conversion of normal pentane to isopentane. Under similar . hand, the reaction conditions may be maintained conditions, wherein the normal pentane contains constant, regardless of the feed stock employed from one-tenth'to 1% of naphthenes, particue except that the time of contact may be varied ' ent, of course, upon the other reaction conditions, usually between about to and about 300° F., pref to suit the particular feed stock. Thus, for ex- _ ' larly cyclopropane and/ or cyclobutane, a conver ample, if the catalyst zone is maintained at a 25 sion of about 75% of the normal pentane con tacting the catalyst will be attained with a grad-- - ' temperature of 75°F. and it is desired'to have ual increase in catalyst activity to the point where the temperature maintainedregardless of the excessive degradation of the'normal C5 feed will feed stock, the treatment of the catalyst with a occur. In operating the process, andin'order naphthene-containing feed stock,‘ for example, a C5 normal pentane containing something like 30 to maintain the activity of the catalyst, one of two possible courses of action are .desirable. 1% or less of Ca. and C4 naphthenes, may be con When the catalyst activity becomesexcessive with ‘tacted at the rate of between about 1 or 2 hours normal pentane, the feed stock may then be until the catalyst activity is such that further shifted to a normal butane isomerization in which treatment with this feed stock will result'in ex cessive degradation of the normal pentane. At 35 no naphthenes are contained, in which case the over activity of the catalyst is, to some extent, the end of this time, the temperature and alleviated by the fact, that normal butane is more amount of catalyst is allowed to remain the same di?icult to isomerize than normal pentane, or the and a naphthene-free feed stock, say, for exam catalyst may be contacted under the same or ple, normal butane, is contacted under the same reaction conditions except that the time of rest-"40 milder conditions with normal pentane substan tially free of naphthenes for such a length of dence of the normal butane in contact with the time that the conversion governed, of course, by aluminum chloride may be somewhat lengthened, the catalytic activity, drops to, say 30 or 40% say to 2 or 3 hours, dependent upon the activity _ of the particular catalyst mass. Ordinarily, the . depending upon the desired economical opera’ time of- contact will be between about 0.1 and 45 tion of the process. It should be understood, of ,course, that ii the activity level of the catalyst is about 20 hours, usually between about 2 and not of any economical importance, the conver about 10 hours, for liquid phase operation and sion may be dropped to 20 or 25% or even lower, between about 15 seconds and about 15 minutes if desired. Once the catalyst activity has dropped preferably between about 20 seconds and about 3 minutes for vapor Operation depending, of 50 to this point, it may be restored to somewhere near the original activity by re-feeding thenaph course, as heretofore mentioned,‘ upon the other theme-containing normal pentane until the ac reaction conditions. tivity has once again risen to somewhere around A number of ‘reactors may be employed in se a conversion of ‘75%. This procedure as described ries or in parallel so that the feed stocks may be interchangeably fed to the various reactors so 55 may be repeated until the catalytic activity is no longer capable of being restored, in which’case that while one catalyst mass is undergoing treat the catalyst is discarded and new catalyst em ment with a naphthene-containing feed, another which has been activated in this manner may be ‘ ployed. - Where it is desirable to accurately control the taining no naphthenes. ,A differential in reac- no amount of naphthenes entering into contact with the aluminum chloride, it may be advantageous tion conditions to suit the optimum isomerizing to remove all naphthenes from the feed stock . activity of the particular feed stock may con and introduce controlled amounts thereof for a veniently be maintained where a plurality of re better control of the catalyst activity. In order actors is employed where such could not be readily accomplished in a commercial operation 65 to remove the naphthenes from a normal par a?in containing at least 4 carbon atoms‘ per if a single reactor were employed. Mechanical molecule, treatment with such compounds as means for agitating the contents of the reactors concentrated sulfuric acid, ?uor and chlor sul when liquid phase operation is employed may be fonic acids, and the like, are found to e?ectively by such devices as motor driven propellers, jets , of restricted internal diameter, turbo mixers, and 70 remove the naphthenes As illustrative of the increased activity of thev the like. A percolation of the liquid feed stock catalyst when employing small amounts of naph through a bed of solid catalyst may also be em thenes, theiollowing example is presented al ployed. Likewise for vapor phase operation, a though it is obviously not- intended that the in bed of catalyst is employed. . The treatment of the reacted mixture upon re- 75 vention be limited thereto. activating the isomerization of a feed stock con 2,406,868 7 Example action conditions and in the presence of a small amount or at least one naphthene taken from the A shaking bomb of 500 cc. capacity was charged with 150 grams of substantially pure normal group consisting of cyclopropane, cyclobutane ' normal conversion of a n-pentane feed using group consisting of cyclopropane, cyclobutane, and alkyl derivatives thereof, said three- and pentane, about 150 grams of aluminum chloride, 5 four-membered ring naphthenes being substan 2.25 grams of cyclopropane, and between about tially the only naphthenes present. 3 and about 4% of hydrogen chloride. The mix 8. A process as in claim 7 wherein the naph ture was heated to a temperature of about 78° thene is present in an amount between about and shaken for about3 hours, at the end of 0.1 and about 4% by weight of the feed. which time the reacted product was foundto con 10 9. A process which comprises isomerizing a tain isopentane to the extent that about 73% normal para?in containing at least 4 carbon of the normal pentane had been converted. Un atoms per molecule substantially free of naph der similar conditions, using fresh aluminum thenes under isomerizing reaction conditions in chloride but in which no cyclopropane was pre the presence or a promoter and a catalyst mass sent, the normal pentane reacted to the extent 15 formed by treating aluminum chloride under iso of only about 44%. merization reaction conditions with a feed stock 'As an example of the promotional eifect of containing small amounts of at least one low naphthenes present in paraf?nic feed stocks, the molecular weight naphthene taken from the 100% AlCh, 22% HCl, a temperature of 75° F., 20 and alkyl derivatives thereof and discontinuing with 2 hours shaking is about 75% whereas when the treatment prior to the activity of the catalyst the naphthenes present are removed by pretreat becoming such as to cause excessive degradation ing the feed with sulfuric acid, fiuor- or chloro of normal paraf?ns containing at least 4 carbon sulfonic acid or by hydrogenation treatment only atoms per molecule under isomerization reaction 44%, 50%, 51% and 48% conversion respectively 25 conditions. is obtained. Having now thus fully described and illus 10. The process as in claim 9 wherein nor mal pentane is employed as the feed stock. trated the character of the invention, what is 11. The process as in claim 9 wherein super claimed as ‘new and useful and desired to be atmospheric pressure is maintained by intro secured by Letters Patent is: 80 ducing molecular hydrogen. 1. A process which comprises contacting at 12. A process which comprises contacting a least one normal para?in containing at least 4 normal para?in containing at least 4 carbon carbon atoms per molecule in the presence of atoms per molecule under isomerizatlon reaction an aluminum halide under isomerization reac conditions in the presence of a small amount of tion conditions and in the presence of a halogen 85 a low molecular weight naphthene taken from containing promoter and a small amount of a the group consisting of cyclopropane, cyclobu naphthene taken from the group consisting of tane, and alkyl derivatives thereof, a promoter, cyclopropane, cyclobutane and alkyl derivatives thereof, said three- and four-membered ring and an aluminum halide followed by the con tacting of the resulting catalyst mass with a naphthenes being substantially the only naph thenes present. naphthene-free feed stock comprising essential ly at least one normal para?in containing at , 2. A process which comprises. carrying out a process as ‘in claim 1 wherein superatmospheric pressure is maintained by the use of molecular hydrogen. least 4 carbon atoms under lsomerization reac tion conditions and in the presence of a pro moter. 45 13. A process as in claim 12 wherein a, con tinuous process is carried out in which the cata 3. A process as in claim‘ 1 wherein the naph thene is present in an amount between about 0.1 lyst is contacted alternately with a naphthene and about 4% by weight of the feed. containing feed stock and a naphthene-free feed ' 4. A process which comprises contacting at stock. least one normal paraffin containing at least 4 50 14. A process which comprises contacting nor carbon atoms per molecule in the presence of mal pentane containing at least one naphthene aluminum chloride under isomerization reaction taken from the group consisting of cyclopropane, cyclobutane and alkyl derivatives thereof with aluminum chloride in the presence of hydrogen conditions and in the presence of at least one hydrogen halide and a small amount of a naph- . thehe taken from the group consisting of cyclo propane, cyclobutane and alkyl derivatives there of, said three- and four-membered ring naph thenes being substantially the only naphthenes present. 55 chloride under isomerization reaction conditions for a period of time only suflicient to maintain about a 75% conversion of the normal pentane to isopentane followed by contacting the catalyst with a normal C5 paraffin hydrocarbon fraction 5. A process which comprises contacting nor 60 substantially free of naphthenes under isomeri mal pentane in the presence of aluminum chlo zation reaction conditions and in the presence ride and hydrogen chloride under isomerizing. of hydrogen chloride and recovering isopentane. reaction conditions while maintaining in the re 15. A process as in claim 14 wherein the naph action zone a small amount of at least one naph thene-free feed stock comprises ?eld butane. thene taken from the group consisting of cyclo 65 16. A process which comprises contacting con propane, cyclobutane and alkyl derivatives tinuously aluminum chloride under isomerizing thereof, said three- and four-membered ring reaction conditions with a normal pentane feed naphthenes being substantially the only naph— stock containing at least one low molecular thenes present. weight naphthene taken from the group consist 6. A process as in claim 5 wherein the naph 70 ing of cyclopropane, cyclobutane, and alkyl de thene is present in an amount between about rivatives thereof until the catalytic activity has 0.1 and about 4% by weight of the feed. 7. A process which comprises contacting nor mal butane in the presence of aluminum chlo-} ride and hydrogen chloride under isomerizing re 75 increased to a high level followed by the treat ment of the resultant catalyst mass with nor mal butane substantially free of naphthenes un- ' til such time as the catalytic activity of the “oases ' i -9 _ 10 catalyst mass is reduced substantially and alter superatmospheric pressure is maintained to in nately and continuously contacting the catalytic sure liquid phase operation. ' mass with the naphthene-containing feed and the naphthene-free feed until the catalytic ac-‘ - 18. A process as in claim 16 in which the re action is carried out in the vapor phase and .tivity of the catalyst has become substantially l the catalyst mass constitutes a plurality of beds. completely spent. CARL O. TONGBERG. 17. A process as in claim 16 wherein sumcient v HOMER J. HALL.