Патент USA US2409262код для вставки
^ Patented Oct. 15, 1946 2,409,250 Unirse STATES ' ATENE' OFFLCE 2,409,260 BUTANE IS OMERIZATION Edmond L. d’ûuville and Bernard L. Evering, Chi cago, Ill., assignors to Standard Gil Company, Chicago, Ill., a corporation of Indiana Application June 24, 1943, Serial No. 492,040 l 13 Claims. (Cl. 260-6835) 2 This invention relates to the production of _iso butane from normal butane and more particularly relates to the isomerization of normal butane and hydrocarbon fractions containing a large propor termittent operation, thus precluding continuous operation. f' Another difliculty inherent in processes using supported aluminum chloride results from the tion thereof into products consisting substantially continuous drop in activity due to the loss of of isobutane in the presence of a speciñc liquid 5 catalyst from the support. Thus with constant catalyst of the aluminum chloride type. feed rate a constantly diminishing conversion re The present application is a continuation-in sults. This change in activity can be compensated part of our copending applications, Serial No. for by varying the activator concentration so 422,983-4, filed December 15, 1941, which in turn that the activator concentration is lowest at the are continuations-in-part of applications which highest catalyst activity and highest for the mini have now matured into Letters Patent 2,266,01l~2. mum catalyst activity for the cycle. This is ob _ Isobutane has in recent years assumed increased jectionable since it does not permit the continuous importance as a basic or starting material for the usecf the optimum activator concentration. In preparation of valuable hydrocarbon products, as 15 practical operation it has been found more feasi well as in the synthesis of many chemical com ble to allow the conversion to fluctuate between pounds. Isobutane can be alkylated, for example, use of the optimum activator concentration. In With oleñns such as propylene, butylene, or other low boiling unsaturated hydrocarbons, or it can predetermined limits giving an average conver over catalysts such as chromic oxide gel or mag ride has an appreciable solubility in liquid butane, operation With supported catalysts is restricted to vapor phase operation. Again'since the isomeri sion measurably below the potential conversion be dehydrogenated to isobutylene thermally or 20 of the given equipment. Since aluminum chlo nesium chromite and the isobutylene polymerized by known means to resins, lubricating oils, or dîisobutylene. The latter compound is easily converted to so-called isooctane by hydrogenation 25 and forms a convenient source of this valuable product for use as premium or aviation fuels. The conversion of normal butane to isobutane has been investigated to a considerable extent and many »processes have been proposed using alumi num chloride as the catalyst. These processes al though adopted commercially are subject to many operational diñiculties which make them rela tively inefficient. In addition the complicated equipment required results in unusually high in stallation costs. Prominent among these proc esses are those which make use of supported zation reaction is exothermic and since supported catalyst makes use of ceramic and clay type Sup ports Which are notoriously poor conductors of heat, special devices are necessary to dissipate the heat of reaction. Finally, since solid aluminum chloride is extremely susceptible to oleñns and 30 higher hydrocarbons special and expensive pre- cautions are necessary to prepare a feed stock which will not change the physical state of the supported aluminum chloride, thus reducing the active surface causing early depletion of the ac 35 tivity of the catalyst. We have found that excellent yieldsof iso butane can be obtained from normal butane with aluminum chloride as catalyst. The principal unusually long catalyst life by subjecting it at diñiculty inherent in these processes results from comparatively moderate temperatures and pres-v the fugitive character of the catalyst. The alumi 40 sures to the action of a special liquid catalyst of` num chloride is not retained permanently on the the aluminum chloride complex type in the support but on account of its appreciable vapor presence of an activator. . pressure is carried along with the eiiluent hydro ‘It is an object of our invention to provide an carbon vapor, Many devices have been tried to improved process for the production of isobutane prevent the escape of the aluminum chloride into 45 from normal butane and hydrocarbon fractions lines Where plugging can result or into equipment containing large proportions of normal butane. the eil'icîency of which or even the operability of Another object is to provide an economical which can be seriously affected. For example, method 4of preparing a product consisting sub beds of clay have been placed down stream from stantially of isobutane by the isomerization of nor the catalyst chamber to adsorb the aluminum 50 mal butane. A further object is to provide a chloride from the efliuent hydrocarbon.I An alter process for the production of isobutane from nor nate method has been to make use of alternate mal butane in which a liquid catalyst of the alumi layers of supported aluminum chloride and clay. num chloride complex type is employed. It is also Although these devices are effective they are an object of our invention to provide a process for but temporary expedients and as such require ín 5,5 the production of isobutane from which high 2,409,260 3 are obtained. It is an object of our invention to tive aluminum” we mean the aluminum con provide a truly continuous process for the conver _tent of hydrolyzable aluminum co-mpounds; sion of n-butane to isobutane. It is an object of i. our invention to provide a process giving a high e., this expression does not include the aluminum content of inactive compounds such as oxides and hydroxides. A complex pre and relatively constant conversion of n-butane to isobutane. It is an object of our invention to pro is an object of our invention to provide an iso 4 range of 67 to 82 large calories per gram atom of active aluminum. By the expression “ac yields of product per unit of catalyst consumed vide a process wherein the optimum activator concentration can be continuously employed. It r pared by the action of aluminum chloride and hydrogen chloride on a light naphtha from nat 10 ural or straight-run gasoline substantially free from aromatic and oleñnic hydrocarbons is em inently suitable for use in the initial starting-up merization process which will give high once through conversion of n-butane to isobutane. It of our process. Neither olefin complexes or aro is an object of our invention to provide a process matic or alkyl aromatic complexes (Gustavson for the isomerization of n-butane which can operate on the liquid phase. It is an object of 15 complexes) are desirable. After the process is started it is only necessary to add make-up alu minum halide or effect continuous or periodic re generation to maintain the catalyst at the desired level of activity. preciably susceptible to deactivation by small 20 Throughout the specification and claims when ever the terms “aluminum chloride-parañinic hy amounts of olefin and higher hydrocarbons. Fur drocarbon complex,” “parañinic complex,” or ther objects, advantages and uses of our invention similar expressions are employed they are in will become apparent from the following detailed tended to designate the liquid complex formed by description read in conjunction with the drawings which form a part of this specification and which 25 the reaction of aluminum halide with a saturated hydrocarbon in accordance With a procedure of show in a schematic manner systems suitable the general type described above. We also refer for carrying out our invention. to our complex as containing “bound” hydro In one of its broad aspects our invention com carbons. This is to designate that the parañinic prises treatingr hydrocarbon fractions containing a large proportion of normal butane in the pres 30 hydrocarbon is joined to the aluminum halide by chemical means and to distinguish the catalyst ence of an aluminum chloride-hydrocarbon com from such catalysts as those comprising a slurry plex at a temperature of from about 120 to about of an aluminum halide in a liquid hydrocarbon. 460° F. and at an elevated pressure, in the pres However, since free aluminum chloride is appre ence of an activator, with intermittent regenera ciably soluble in aluminum chloride complex tion of the catalyst to a mobile liquid form or catalyst not all of the aluminum chloride is chem with addition of makeup aluminum chloride in our invention to provide an isomerization reactor wherein the heat of reaction can be readily dissi pated. Finally it is an object of our invention to provide a process the catalyst of which is not ap ically bound to hydrocarbon. The complex preferably contains from about 16% to. about 40% hydrocarbons based on the total catalyst on solution to maintain catalyst activity. The feed stock for our process can be a rela tively pure normal butane, but, generally speak ing, essentially saturated hydrocarbon fractions 40 a weight percent basis. composed predominantly of the butanes and con taining a large proportion of normal butane are preferred, since they are much `more readily available. Suitable charging stocks, for exam ple, are the butanes obtained by fractionating the natural gasoline recovered from natural gas or “distillate” wells by conventional methods or the residual gas from a catalytic polymerization, hydration or alkylation unit operated on a “plant butane” cut, the oleñns in the cut ‘being substan 50 tially completely removed by the polymerization If desired, the catalyst can be fortified or maintained at desired activity by dissolving sufficient aluminum halide in the aluminum halide-hydrocarbon complex or in the normal butane feed. The solubility of aluminum chloride in butane is approximately as follows: Temperature Wt. percent of ~ . A1013 dissolved Lbs. of AlCls per bbl. of butane The butane fraction charged is 0.01 preferably substantially completely saturated, . 3 . (i l. 5 2. l 5.5 3. l 4. 3 ll. 3 or alkylation. i. e. free from olefins, and it is also substantially free from moisture. U. (l2 The active liquid aluminum halide-hydrocar bon complex used in accordance with our inven tion may be prepared by the action of an alumi num halide, such as anhydrous aluminum chlo ride or aluminum bromide, and an activator af fording a hydrogen halide on a substantially sat Thus by simply controlling the amount and tem perature of that portion of the butane charge which is passed through a solution tank, the 60 quantity of make-up aluminum chloride may be urated fraction containing, for example, paraffin regulated with great precision. The aluminum chloride-hydrocarbon catalyst exhibits great af hydrocarbons at a temperature in the range from about 50° F. to about 225° F. or more. Such a tracts substantially completely dissolved alumi ñnity for free aluminum chloride and hence ex complex catalyst may be prepared, for example, 65 num chloride from the butane feed. By introd ducing the makeup at a rate within the approxi 2,300,249. Its activity may be measured by its mate range of 0.1 to 1 pound per barrel or the heat of hydrolysis as determined by any well more limited range of 0.2 to 0.5 pound per barrel known calorimetric method. Note U. S. Patent of total butane charged, the added makeup is ef 70 2,308,560.) In the case of aluminum chloride fectively removed from the solution by the com complexes such heats of hydrolysis are usually in plex and is not carried from the reaction zone in the approximate range of 60 to '75 large calories solution in the effluent product. per gram atom of active aluminum and in the The above solubility data is based on substan case of aluminum bromide complexes such heat tially pure normal butane and fresh aluminum in the manner described in our U. S. Patent of hydrolysis is usually in the approximate 75 5 2,409,260; chloride. It has been found, however, that the 6 i. e. the tower may be about 1/¿ to 3A full of com rate of solubility decreases in time when the plex. The column of complex in the'tower should _butane contains impurities due to an apparent be at least ñve feet deep and preferably twenty contamination of the aluminum chloride. This to thirty feet deep or more. Since the top of the can be compensated for easily by increasing the column of complex is below the level at which temperature of the butane and/or decreasing the reaction products are withdrawn and since the rate of flow of the butane through the aluminum amount of make-up catalyst added and spent chloride tanks. Also the difüculty may ‘be largely catalyst withdrawn is quite small, the column of remedied by passing through the tanks recycle complex in the reaction zone is relatively sta n-butane which has already been passed through 10 tionary. The term “relatively stationary” does the reactors. not mean quiescent because there will of course The drawings which form a, part of this speci ñcation are illustrative of two types of systems according to the present invention. Figure 1 is a ilow sheet of a system for carrying 15 out the invention by adding make-up aluminum halide in complex; and l‘ce a certain amount of turbulence within the column itself. The term “relatively stationary” means‘rather that the catalyst column is rela tively nxed or stationary with regard to charging stock flow as distinguished from concurrent and countercurrent'i'low respectively. s Figure 2 is a ñow sheet of a system for prac The isomerization reaction is carried out at ticing the invention by adding make~up alumi temperatures within the range from about 120° num halide in at least a part of the entering 20 F. to about 400° F., preferably about 212° F. butane stream. Heat can be supplied by passing the butane and Referring now to Figure 1, a n--butane feed hydrogen chloride solution through a heater 2| ' stock of the type described above enters mixing tank I0 through line || under pressure imposed by the aid of pump I2. An activator such as an hydrogen halide or a compound añording an hydrogen halide under the reaction »conditions enters mixing tank ID through line I3 and pump in line I5 and/or by the use of a heating jacket or other heating means 22 about section I9 of isomerizer I8, any suitable heating medium en tering through line 23 and being discharged through line 24. Only the lower part of the tower need be jacketed for temperature control, I4. As an activator we prefer to employ an hy and the whole tower covered by eiîective insulat drogen halide such as ‘the chloride or `bromide 30 .ing material, or the heating jacket can extend although we may use materials which yield hy about the enlarged section as well as the narrow drogen halide during the reaction.Y section. depending upon whether it is deemed Wherever the term “activator affording an hy preferable to maintain the entire reactor at ap drogen halide” or a similar expression is used proximately the same temperature or to have the throughout the specification and claims, it is in two sections at diiîerent temperatures. Catalyst tended to include not only such substances as is added through line 25 and line 26 having valve 27 therein to the upper portion of tower I9 while the reactants enter near the base of this tower alkyl halides, organic' chlorides and chlorine, but also the hydrogen halides themselves. For the sake of simplicity the process will be described relative to the use of hydrogen chloride, our pre through a spraying means 28er other means for 40 dispersing the reactants through and in intimate ferred activator. In mixing tank I0 the normal Contact with the liquid catalyst if it appears butano feed is partially saturated with hydrogen desirable. ' chloride or other activator until the concentra In order to maintain the activity of the alumi tion of hydrogen halide, based on the total feed, num halide-paralîinic hydrocarbon complex, the lies between about 0.1% and about 20% or pref 45. complex can, if desired, be by-passed from line 25 erably between about 3% and 6% by weight'. through line |22 and heater |23 to a tower I 24 The butane and hydrogen chloride in liquid phase containing beds of solid aluminum chloride. are then pumped through line I5 and line IB Valve |25 in line |22 is open and valve |2t` in line having valve Il therein to isomerizer I8. Al 25 is closed. In heater |23 the complex is heated though our process can operate in either the 50 to such a, temperature that just suflicient alumi vapor or liquid phase, the reaction is preferably num chloride is dissolved to maintain the catalyst carried out with the reactants in the liquid phase, at the desired activity and the complex is allowed and the pressure can lie within the range from to flow over or otherwise contact the solid alu about 100 to about 2000 pounds per square inch, minum chloride in tower |24. Fresh aluminum depending to a large extent upon the tempera 55 chloride can be added to tower |24 via line |21. ture at which the reactor is maintained. A pre The fortiñed complex then passes from tower |24 ferred pressure will be in the general vicinity of through line §23 to line 25 at a point beyond about 500 pounds per square inch, i. e. about 300 valve |20. y to 600 pounds per square inch. The fortiiìcation of the complex may be con Isomerizer I8 can ybe a reactor in the form of 60 trolled by means of valve |25, heater |23 and the an elongated tower I 9 topped by a comparatively quantity oi solid aluminum chloride in tower |24 short wide section 20. Other types of isomeriza so that the amount of aluminum chloride taken tion reactors such as those having mechanical up lby the complex may be regulated to any de mixing means therein or comprising elongated sired amount. Usually it is desirable to intro coils. etc., can be substituted if desired, and it is 65 duce the -iortiiied complex into the reaction zone equally feasible to employ a tower having the in such amounts that about 0.1 to about 1 pound, same diameter throughout its length, leaving the preferably about .2 to .5 pound, of dissolved alu upper part free of catalyst to act as a “settling minum chloride is introduced into thefreaction section” or a separate separator can Ibe employed zone per barrel of charging stock introduced for this purpose. The narrow part of the tower 70 thereto. I9 is filled with catalyst of the type described The enlarged section 20 of îsomerizer I8 can approximately to the point where the narrow act as a “settling section” or separator allowing portion I9 expands to form the enlarged section any mechanically occluded catalyst to separate 20. With a tower of uniform diameter the com out from the hydrocarbons and fall back into plex may extend to a relatively high level therein; 75 tower I9. The products from'the isomerization 7 reactor including unconve?ted' normal angabe une 51; However, »itjisj "ffeq'ue?uy desistere 'ai butanes,t recover the Vis‘obutan'e'as a comparativelypure any' degradation products suchl as propane and fraction and therefore the normal and isobutane lighter hydrocarbons, as well as hydrogen chlo mixture can b_e passed .to fractionator 58 by open ride, and isobutane pass overhead from isomerizer I8 through line 29 to line 30 having valve 3| Ci ing valve 59 inline 60. Fractionator 58is any conventional fractionating equipment for the therein through cooler 32 to separator 33. The separation of components of various boiling points “weight space velocity” in the reactor will vary ancl'isV provided with the necessary cooling and widely depending on the activity of the catalyst, heating means -for separating the normal> butano temperature of operation, and degree of isomer i'zation required. In general it will fall within l0 from the isobutane. The desired isobutane passes the limits of 0.1 to 100 pounds of butane per hour per pound of aluminum chloride in the reactor. The volume space velocity for catalysts of aver age activity (about 60 to 70 large calories per gram atom of active aluminum in the case of aluminum chloride) is within the approximate range of .2 to 4 volumes> of liquid butane charged per hour per volume of complex in the reaction z'one or column. The pressure in separator 33 can be substantially less than that in reactor I8, a pressure reducing valve 34 in line 30 being pro vided for this purpose. Y Separator 33 diagramma-tically illustrates a separation system for separating hydrogen chlo ride and gases on one hand and catalyst material on the other hand from the liquid product stream. While a single vessel is illustrated in the draw ings it should be understood that any number of settling chambers, stripping columns, etc., may be employed for this purpose. Separator 33 may be operated at substantially reaction tempera ture and may act as a combined settler and strip per. The hydrogen chloride is taken overhead through line 35, valve 36 in vent line 3l is closed, valve 38 in line 39 is opened, and valve 40 is likewise open so that the hydrogen chloride is simply recycled to line I3. When the gases leav ing the separator through line 35 contain un desirably large amounts of gaseous hydrocarbons, valve 45 may be closed, valve ¿EI opened and the gases thus passed through line 42 to separator 43 wherein by absorption means or other methods the hydrogen chloride may be separated from hy drocarbons. The hydrogen chloride can then be overhead through line 6Iv to storage (not shown) while the normal butano is withdrawn through line 62 and can be recovered as 4such by opening valve 63 in_line 64,"b'ut preferably is recycledto the isomerization reactor by opening valvev 65 in line 66 which joins line Il. Any hydrocarbons heavier than butane can be withdrawn Vthrough line 62a and discarded or used otherwise 'as de scribed. ' - We have thus far described our process as one employing a single reactor I3. However, itis often desirable formore complete conversion to employ the reactorsin series. Accordingly, the products from line" 29 can` if desired, bedirected to isomerizer 61 by opening valve 68 in line 69 leading from line 29, valve 29a being closed. The products pass from line 'I0 to a dispersing means 'II in the elongated tower 'I2 of isomerizer 6'I, passing up through the catalyst pool to the en larged portion 13. Catalyst can be added from line 25 by opening valve 'I4 in line l5. The prod ucts pass overhead from isomerizer 6'I through line '16, valve 'I'I being open, to line 39 and the separator andv fractionator previously described. Another desirable mode of operation is to em ploy isomerizer IS‘forr the conversion of normal butane> to isobutane until the catalyst therein is degraded to a point where it is no longer par ticularly effective for promoting the reaction; When this occurs valve I'I in line I6 can be closed and valve 'I8 in'line 'I9 opened, directing the feed stock through line 'I0 to is'omerizer 61. In this event, of course, valve 2'! in line 26 will be closed, valve 'I4 in line 'I5 being opened. While isomer' returned by line 44 and line 39 to line I3 and 45 izer riì'I is “onstream” the'catalyst in isomerizer I8 can be regenerated and alternatively when the hydrocarbons vented from the system Ithrough isomerizer I8 is “on'stream” the catalyst in iso-` line 45. _ merizer B'I can be regenerated. When cooler 32 apprcciably lowers the temper ' The regenerationis preferably carried out by ature, for example to 100° F. or lower, most of the hydrogen chloride may remain in solution in 50 the use of hydrogen only in the pre-sence of an hydrogen halide, if desired, at superatmospheric the liquid product but in this- case light hydro pressures. Hydrogen vfromv any source enters carbon gases may be purged from the system by through line 89 and is directed, for example. to closing valve 38 and opening valve 36 to vent line the base of tower I9 by opening valve 8l in line 37. In this case, however, a subsequent s-tripping of the hydrogen chloride out of the liquid product 5 5 82. The temperatures employed for regeneration will lie within the rangel ef from about 200° F. to is desirable to avoid unduly large activator losses. about 350° F. and'pressures of from about 500 t0 Any catalyst carried along mechanically or dis 1500 pounds per square inch are employed,_prefsolved in the products can be recovered from erably 600 pounds to 1000 pounds per square separation system 33, the lower temperature serv ing to precipitate any dissolved aluminum chlo 60 inch. A minor amount of hydrogen chloride can be added from line E3 by opening valve Sil if de ride. Entrained complex together with precipi sired. During the regeneration of the catalyst in' tated catalyst accumulates as a liquid and may isomerizer IB valve 3! in line 39 and valve 63 in be withdrawn through line 46 either through line 69 will be closed while valve 85 in line 85 valve A‘I and line 48 or preferably through valve will be open to permit the escape of hydrogen, .f 49 and line 50 which joins line 25. which'can Je returned to the hydrogen source The isomerized product, together with uncon (not shown). For theregeneration of the cat verted normal hydrocarbons, is withdrawn from alyst in isomerizei` 5'! hydrogen input line 8'! separator 33 through line 5I and passed through with valve 88 is provided aswell as hydro-gen wash tower 52 wherein any last remaining traces of catalyst and/or hydrogen chloride are removed. 70 discharge line 99 having valve 90 therein. Re generation per se is described in more detail in Water or an alkali wash, which enters through our U. S. Patent 2 293,891. line 53 and is discarded through line 54, can In another mode cfoperation the catalyst can be employed. The washed products are with be continuously or intermittently withdrawn from drawn from wash tower 52 through line 55 and can be recovered as such by opening" valve 56 in' 75 isomerizers I8v vand/0r 6'I via lines 9I andl92, 9 2,409,260 respectively, having valves 93 and’94 therein, to line 95 while fresh catalyst is continuously added 10 tion is made between isobutane, propane and lower boiling hydrocarbons on the one hand " from line 25. The spent catalyst can ‘be discard which are withdrawn from the top of the tower |30 and normal butane, pentane and higher boil is separately regenerated. To accomplish this, 5 ingrhydrocarbons on the other hand which are valve 98 in line 99 is opened, the catalyst pass withdrawn from the bottom of the tower |30 ed by opening valve 96 in line 91 but preferably ing through heater |99 to regenerator |0|. Hy drogen is added from line |02 and hydrogen chlo ride from line ||4, the same conditions of pres sure and temperature being maintained in regen 10 through line í3| to the normal butane tower |32. rl‘he eliluent from tower |32 consists predomi nantly of normal butane although minor amounts of other saturated hydrocarbons can be tolerated. erator |0| as were previously set forth for regen eration of the spent catalyst in the reactors. No Pentane and higher boiling hydrocarbons are re moved from the Abottom of the normal butane tower |32 through line |33. The normal butane other promoters or regenerating agents are nec essary, the hydrogen and hydrogen chloride alone stream is passed through line |34 from the top serving to reactivate the complex to a liquid mo» 15 of tower |32, through cooler |35 to drum |36. bile form. The regenerated catalyst plus hydro Part of the condensed normal butane stream may gen is withdrawn from regeneratcr |0| which be returned as reflux to the normal butane tower has been providedV with a mixer |03 or other through line |31 while the remainder is passed means for insuring contact between the hydrogen through line |38, heater |39 to any one or more and the catalyst, through line |04 to separator of the reactors |40, |4|, |42 and |43. If desired |05, line |04 being provided with a pressure-re the normal butane stream may be by-passed ducing valve |06. The hydrogen, with or with around heater |39 through line |44. An activator out hydrogen chloride, passes overhead through line | 01 and can be discarded through line |08 by opening valve |99 or recycled by opening valve ||0 inline ||| which joins line |02. Any hydro carbons separated from the catalyst by the re generation step can be discarded through line ||2 while the regenerated catalyst is withdrawn through line ||3 and directed to line 25 where 30 affording hydrogen halide, such as hydrogen chloride per se is introduced through line |45 to the normal butane'stream in line |40 where it is mixed with the normal butane in amounts of about l to 10% or preferably 3 to 6% by weight based on total butane charged. A portion of the normal butane is withdrawn from line |43 (prior to the point at which hydrogen chloride is added) it can be re-utilized in the process. In no case through line |41 and passed through towers |48 is the catalyst sludge regenerated to 'such an and |49 which contain solid aluminum chloride. extent that pure aluminum chloride is formed, as Additional aluminum chloride may be introduced has been suggested previously in the art, We into the towers |48 and |49 at |50 and |5| respec prefer to use a catalyst in the form of a mobile 35 tively. As shown in the drawings line |41 is pro complex and not as a pure aluminum halide. vided with valves |52, |53 and |54 so that the It is also contemplated that when using the portion of the normal butane may be passed reactors in series the catalyst from one reactor through either one of the towers |48 and |49 or may be directed to the other reactor, in the event through vboth towers simultaneously. In the alu that the catalyst is not substantially or com minum chloride towers the normal butane dis pletely spent when it is withdrawn from the re solves aluminum chloride in amounts controlled actor. Such a mode of operation is particularly by temperature and amounts of butane passed advantageous if the reactors are maintained at therethrough and this solution passes through different temperatures, reactor 91 being main lines |55 and |56 to line |51 whence it is intro tained in the lower portion of the temperature duced into any one or more of the reactors |40, range described and reactor 61 in the upper por |4|, |42 and |43 through lines |58, |59, |69 and tion of the range, for example. The higher tem |6| respectively. Obviously if desired the number perature will allow the use of the catalyst to a greater degree of conversion per unit of catalyst, of reactors may be increased or decreased de pending upon the size of the reactors, the capac while the lower temperature permits a greater 50 ity of the system and other factors. The amount degree of conversion per volume of feed. A part of aluminum chloride dissolved in the normal or all of the partially spent catalyst can be di butane and hence the amount delivered to the rected from one reactor to another, and alter reactors is regulated by the amount and tem natively a part can be sent to one of the reactors perature of the butane feed passing through the and the remainder withdrawn for regeneration. 55 towers |48 and |49 so that the activity of the This can be accomplished by opening valve IIS catalyst in the reactors may be controlled readily and easily. It is desirable to introduce from about sending the partially spent catalyst to the other 0.1 to 1 pound, usually about .2 to .5 pound of reactor by opening valves ||8 or ||9 in lines ||1 dissolved aluminum chloride into the reaction or |20,A joining lines 26 and 15 respectively, valve 60 zone per barrel of total charging stock. | 2| in line 95 being closed. By the proper ad Each of the reactors |40, |4|, |42 and |43 con justment of valves ||6 and |2| a part of the cat tains a column of aluminum chloride-hydrocar alyst can be routed as above described and a part bon complex as described hereinbefore. Since withdrawn for regeneration. Ordinarily, with the amount of make-up catalyst added and spent drawal and recycle of thev spent catalyst to the 65 complex withdrawn is quite small, the column of same reactor without intervening regeneration complex in the reaction zone is relatively station or aluminum chloride additives is not contem ary. The term “relatively stationary” does Vnot plated since it is expected that the catalyst will mean “quiescent” because there will of course be be retained within the reactor until it is no longer a certain amount of turbulence within the column effective for promoting the isomerization reac 70 itself. The term “relatively stationary” means tion. rather that the catalyst column is relatively ñxed Another system for isomerizing normal butane or stationary with regard to charging stock flow is shown in Figure 2. In this figure the feed con as distinguished from concurrent and counter taining normal butane is introduced through line current iiow respectively. This column should be l 29 >to the isobutane tower |30 in which a separa >75 at least about 5 feet in depth and should prefer in line || 5 which leads from lines 9| -or 92 and 2349.932@ . >1`1 ably _be about 20 to‘30 feet. As .shown inthe drawingsA the normal butane is introduced at a low point in the column while the make-up alu minum chloride dissolved in a portion of the bu tane feed is introduced at a higher point in the column. The conditions existing in the reactors are similar to those previously mentioned and are favorable to the isomerization of normal butane to isobutane; the pressure is suñicieht to main _tain liquid phase conversion conditions, i. e. is wit`.in the approximate range of 100 to 2000 pounds preferably about 300 to 600 pounds per _square inch and the temperature is within the 12 gasesçwill be very small because under the con ditions in accumulator |99 the hydrogen chlo ride is enieny dissolved in the liquid productl stream. The overhead from the isobutane tower |30 contains not only the isobutane produced by the system but also any isobutane which may be pres ent in the feed in line |29. In addition, the over head may contain propane. The overhead is with, drawn through line |92, condensed in cooler |93 and introduced into tank |90, A portion ¿of- the condensate may be pumped back to the isobutane tower as reflux while another proportion is passed approximate range of 120° F. to L100“ F., prefer ably about 200° to 250° F. As stated above we prefer to operate our process in the liquid phase although we may also operate in vapor phase. The space velocity with a catalyst of good activity Ashould be within the approximate range of .2 _to 4 through line |95 to the depropanizer |96. The bottoms from the depropanizer consist essentially of isobutane and can be withdrawn through line |91> to storage. The overhead from'the Vdcpro panizer, consisting of propane and any lower boil-, ing hydrocarbons that> may be present, is with A5 in the case of the system illustrated in Fig ure 1 the butane stream passes upwardly through 20|. volumes of total butane charged per hour (liquid 20 drawn through line |98 and cooler |99 to‘reñux drum 209 from which a portion of the condensate basis) per volume of complex in the conversion may be returned to the depropanizer as reñux and zone. rl_`he vertical flow rate may be about 0.1 to another portion withdrawn through valve‘d- line 1 foot, e. g. about .5 foot per minute. the reactors as a dispersed phase in a continuous The spent catalyst complex may be withdrawn from the reactors i610, MI, |42 and |43 through by line |66 through a pressure reducing valve |91, catalyst complex may be withdrawn from the lines 202, '203, 204, 205 and line 206 to catalyst complex phase. At a point near the top of the drum 201. Likewise active catalyst complex may reactor the products of isomerization form a con also be withdrawn from any one or more ’of the tinuous phase and any catalyst complex which is carried into this phase will tend to settle out 30 reactors to the storage drums when occasion de mands and such active catalyst- may be returned and return to the continuous complex phase in to any one or more of the reactors by means of the lower part of the reactor. The products of pump 298 and line 209 and thence through line reaction are removed from the top of the reactor 20,6 and lines 202, 203, 204 and/0r 205. Spent through lines |62, |63, |94 and |65 and thence catalyst drum through line 2|0. When 'spent complex is withdrawn to drum 201 it passes through a pressure-reducing valve in line 206 which permits the escape of hydrogen chloride about 40 to 100° F. Settled catalyst complex may be returned to 40 and hydrocarbon gases released by the reduction a cooler |078 to an accumulator |69 which may be operated within the range of about 90 to 150 pounds gage pressure and at a temperature of the reactors through line |10, pump |1| and lines |12, |13, |14 and |15. That portion of the liquid products which passes over the bañie |16 in the accumulator |99 is pumped through line |11 to column |18 wherein the hydrogen halide acti vator is stripped. Column |18 may be operated at a pressure of about 450 with a top temperature of about 125° F. and a bottom temperature of about 270° F. The activator is withdrawn from the top of the stripping column |18 through line |19 and returned to the normal butane feed pass ing through line |46. The bottoms from the stripping column |10 are Withdrawn through line |30, cooler |8| and subsequently purified by caustic which maybe of pressure on the complex. These gases are vented through line 2| i. To prevent corrosion and colring in drum 201 the spent complex is protected from moisture and air by gas blanket ing the drum with either dry inert or hydrocar bon gas introduced through line 2 | 2. As an example of the process according to the present invention a plant stream consisting pre-v dominantly of normal butane was charged through `line |29 at the rate cfV one gallon per hour for sixty hours to the isobutane towerI |30. The bottoms 'comprising normal 'butane and higher boiling hydrocarbons were subsequently fractionated in tower |32. The. normal butane stream which was taken overhead through line |34 and subsequently passed> through line |38 was heated by' heater |39 to a temperatures of ap proximately 170°> F.. This lontane stream which includes recycle normal butane derived from line through line |94, or, if desired, in the case of only partially spent caustic, it may be recycled to the 60 |90 is. fed to the> reactors at the -rate of approxi mately 1.8 gallons per hour, Approximately 50% settler through line |85. The treated products of the normal butane stream in line |46 is passed are withdrawn from the caustic settler through through the aluminum> chloride drums |48 and line |05 admixedwith wash water which is intro |49 wherein a solution of aluminum Vchloride in duced through line |81 and passed- through a mixer to a water settler |99 where a separation 65 normal butane is formed. During the 60 hour run .4 pound of aluminum chloride was dissolved occurs; the water being withdrawn through line by the normal butane. This is equivalent to -a |99. The product which hasY thus been washed product yield of 105 gallons of isobutane per is passed via line |90 to the isobutane tower |39. pound of make-up aluminum chloride. Hydro During the course of the isomerization reaction gen chloride was added to the normal butane various gaseous products may be formed which stream through line |45 in an amount equal to must be vented from the system in order to pre 4.5 weight percent of reactor charge, The space vent the accumulation thereof in the system. A velocity within the reactors was rapproximately vent is provided on the accumulator |09 and such 0.8. »In order to effect the isomerization ofV the gases may be removed from the system by. line |91. The loss of hydrogen chloridewith these 75 normal butane the reactors were maintained- at introduced through line |82 and this mixture is passed through a mixer to a caustic settler |83 from which spent caustic may be withdrawn 13 2,409,260 14 a temperature of about 215° F. and at a pressure of about 400 pounds per square inch. The prod uct stream in line |66 passes through the pres sure reducing valve |61 to the accumulator |69. The conditions therein are maintained 'at ap proximately 90 to 100° F'. and 290 pounds per square inch. After separation from any catalyst complex which may have been carried over the product stream is passed to the stripping column plex in amounts suñicient to maintain the hydro carbon content of the complex within'the range of about 16% to about 40% by weight. 3. The method of converting normal butane to isobutane which method comprises continuously introducing a normal butane charging stock at a low point in a relatively stationary column of liq uid aluminum halide paraffinic hydrocarbon complex, introducing a small amount of a hydro |73. This column was maintained at a pressure l0 gen halide activator into said column of complex, of about 300 pounds per square inch and had a maintaining said column at a temperature effec top temperature of 95° F. and a bottom tempera tive for converting normal butane to isobutane ture of 235° F. In this case a recycle hydrogen and maintaining a column height suñicient to chloride was sent to an adsorber. The bottoms effect substantial conversion as the butane passes from the stripping column were after purification 15 upwardly therethrough at a temperature below returned Ato the isobutane tower |30. It was about 300° F. and at a pressure suiiâcient to main found that whereas the charging stock for the tain the butane in liquid phase, continuously re reactor contained only approximately 9% isobu moving reaction products at conversion pressure tane the product stream in line |90 contained and in liquid phase from said relatively station approximately 48% isobutane, The overhead 20 ary column to a settling zone of suñ‘ìcient cross from the isobutane tower was stripped to remove sectional area to permit the settling out of a sub lower boiling hydrocarbons and the isobutane stantial amount of entrained complex from liquid product, containing 93% isobutane, was obtained. butanes leaving said column, adding make-up While we have illustrated our invention by ref aluminum halide to said complex iny amounts erence to the specific iiow diagrams, it `should be 25 sufficient to maintain the hydrocarbon content emphasized that these are by way of illustration of said complex within the range of about 16% only and not limitations on the scope of our in to about 40% by weight separating activator and vention. Moreover, for the sake of simplicity, any residual catalyst from liquid reaction prod various details have been omitted from the draw ucts and fractionating said products to obtain a ings and description, such as heat exchange fea 30 fraction consisting essentially of isobutane. tures, pumps, valves automatic control means, 4. The method of converting normal butane etc., which omissions will be readily understood to isobutane which method comprises maintain and supplied by one skilled in the art wishing to ing a column of liquid aluminum halide-par practice our invention. aftinic hydrocarbon complex in a reaction zone, 35 incorporating an aluminum halide into said com We claim: 1. The method of producing isobutane which plex in amounts sufficient to maintain a hydro method comprises reacting a saturated hydrocar carbon content in said complex within the range bon with aluminum chloride in the presence of of about 16% to about 40% by weight, intro hydrogen chloride under conditions for producing ducing a normal butane charging stock into said a liquid aluminum chloride hydrocarbon com 40 reaction zone at a ñrst level at a low point in said plex having a hydrocarbon content within the range of 16% to 40% by weight based on total complex, continuously contacting a charging stock consisting chieñy of normal butane and substantially free from oleiins with said complex column, said column extending from said lirst level up to a higher second level, introducing a hydrogen halide activator in said column, passing liquid charging stock upwardly through said col umn as a dispersed phase in said column of com in the presence of a hydrogen halide activator plex between said iirst level and said second level, maintaining a separation space in said reaction zone above said second level wherein complex under conversion conditions of temperature, pres sure and space velocity for effecting isomeriza tion, continuously separating hydrocarbon prod may separate from upiiowing liquid conversion ucts from said complex at substantially con 50 products and be returned to said column of com version temperature and under a pressure suffi plex, withdrawing reaction products at a third cient to maintain at least a part of said product level which is higher than said second level in in a liquid phase, and adding make-up aluminum said conversion zone and separating hydrogen chloride to said complex employed in the contact halide and any residual catalyst from the with ing step at such a rate as to maintain the hy 55 drawn products. drocarbon content of the complex within the 5. The method of converting normal butane to range of 16% to 40% by weight. isobutane which method comprises contacting in 2. A process for the conversion of normal bu a reaction zone a normal butane charging stock tane into isobutane which process comprises substantially free from oleñns with a liquid alu maintaining in a conversion zone a relatively sta 60 minum chloride-paraiìnic hydrocarbon complex tionary column of liquid aluminum chloride parafiinic hydrocarbon complex at isomerization temperature and under suiiicient pressure to maintain liquid phase conversion conditions in said coulmn, continuously introducing a normal 65 containing an amount of hydrocarbons within the range of about 16% to about 40% by weight based on total complex, eiîecting said contacting at a temperature within the range of 120° F. to butane charging stock at a low point into said col umn, introducing a hydrogen chloride activator into said column, passing chargingstock as a dis 400° F. and under a pressure of at least about 100 pounds per square inch and sumcient to main tain a liquid hydrocarbon phase in said reaction zone, introducing hydrogen chloride into said persed phase upwardly through said column, con reaction zone in amounts within the range of .1 tinuously separating complex from butanes leav 70 to 20% by weight based on charging stock, em ing the top of the column, continuously return ploying a space velocity within the range of .1 ing separated complex to the upper part of said to 100 pounds of butane per hour per pound of column, continuously withdrawing separated bu aluminum chloride in the reactor, adding alumi tanes at a point above the top of said column and num chloride to said complex in amounts suffi adding make-up aluminum chloride to the com 75 cient to maintain the hydrocarbon content of 2,409,260 1-5 said complex within said range of about 16% to about 40% during the conversion and removing catalyst and activator from reaction products. 6. The method of claim 5 wherein the con version temperature is in the general vicinity of about 200° F., wherein the conversion zone 'is un der` suñîcientpressure to maintain substantially liquid» phase conversion conditions, wherein 16 charging 'stoclc‘stream consisting chiefly of nor' mal butane and substantially free from oleiins at a low level in a relatively stationary column of liquid aluminum chloride-parai’ñnic hydrocarbon complex conversion zone, employing in said column a complex having at least 16% by weight but not more than 40% by weight hydrocarbon component in its composition, adding a hydrogen halide activator to the column, passing the dis make-up aluminum chloride is introduced to the reaction zone at the rate .of about .l to 1 pound 10 persedv charging stock upwardly through the col umn under conversion conditions of temperature, perubarrel. of total charging stock introduced pressure and space velocity for effecting isomeri thereto,whereinhydrogen chloride is introduced Zation, fortifying said complex to maintain it in into. saidconversion zone at the rate within -the range,..of~about 3% to 6% by weight based on total; charging stock and wherein the space ve locity.- is within the vrange of„.'.2 to 4 volumes of charging-‘stock per hour per volume of complex active state by adding aluminum chloride thereto, 15 separating hydrocarbons as a liquid phase from the column of complex and continuously with drawing a hydrocarbon stream from the upper part of saidconversion zone. in‘- the conversion zone. l l1. The method of claim l0 wherein the rate »FLA‘The‘ method; of. claimA 5 wherein said con tacting is effected by introducing said charging 20 of aluminum chloride addition is within the range of .l to l lb. per barrel of stock charged. stock at-the Ybase ‘of a‘column of liquid catalyst 12. The method of claim 10 wherein the rateof complex which is at least about 5 feet in height. aluminum chloride addition is such as to main . 8. >The method of-.olaim Y5 wherein saidy con tain in the composition of the complex at least tacting `is effected'by introducing said charging stockA at `the base ci a column of_ liquid catalyst 25 about 16% but not more than about 40% by weight of hydrocarbon components. complex .which is within the range of 5 to 30 feet 13. The method of producing isobutane which in height. comprises continuously passing a charging stock 9.. The method ci producing isobutane which consisting chieñy of normal butane and substan method comprises continuously dispersing a charging stock stream consisting-chiefly of nor 30 tially free from olefins upwardly through a col umn of liquid aluminum chloride-paraffinic hy mal butane and substantially free from oleñns at drocarbon complex in the presence of added hy a low level into a relatively stationary column of drogen chloride at a temperature, pressure and liquid aluminum halide-paramnic hydrocarbon space velocity for eiîecting isomerization under complex in'a conversion zone, employing in said column a complex having at least 15% by Weight 35 liquid phase conversion conditions, producing said complex by reaction of aluminum chloride in the but not more than 40% by weight of hydrocarbon presence ofhydrogen .chloride with a saturated component in its composition, adding hydrogen hydrocarbon which is substantially free from ole halide activator to said column, passing said dis ?lns and aromatics and by employing an amount persed charging stock upwardly thro-ugh said col umn under conversion conditions of temperature, 40 of reactants in said complex producing step so that the complex kin the isomerizing step will pressure and space velocity for effecting isomeri have a hydrocarbon content within the range of zation, fortiiying the complex by addition of alu 16% to 40% by weight based on total complex, minum halide `for maintaining its activity, sepa and maintaining the activity'of the complex dur rating hydrocarbons as a liquid phase from the column of complex, and continuously withdraw 45 ing the continuous passage of charging stock ing separated hydro-carbons from the upper part of said conversionzone` ' f ` 10. The method _of producing isobutane which method comp-rises continuously dispersing a therethrough by adding make-up aluminum chlo ride to said complex. . ` EDMOND L. D’OUVILLE. rBERNARD L. EVERING.