Патент USA US2404649код для вставки
Äuìy 23, î946. M; NEUHAUS IsoMERIzING HYDRocARBoNs Filed Jan. 26, 1945 mw60 Al * 2,404,649 _ Patented `Íuly 23, 1946 2,404,649 « UNITED 'STATES PA'rsN'r4 orrlcl:i IsoMERIzING HYDRooAR‘BoNs Max Neuhaus, Bronxville, N. Y., assignor to The ILl‘exas Company, New York, N.- Y., a corporation of Delaware Application January 26, 1943, Serial No. 473,581 10 Claims. 1 t This invention relates to isomerizing hydrocar bons and more particularly to effecting the con version by contact with a liquid isomerization catalyst. . Y _ 2 . \ l carbons and some higher boiling `material that maybe formed in the reaction. These phases may be separately withdrawn, the «catalyst phase being recycled. . The with drawn hydrocarbon phase is advantageously sub jected to fractionation or fractional distillation The` invention contemplates eiîecting isomeri zation of hydrocarbons in a reaction zone where in hydrocarbons undergoing conversion by con so as to separate unreacted hydrocarbons from any higher boiling material present, such higher tact with a liquid isomeri‘zation catalyst are sub boiling material being discharged from the sys jected to continuous countercurrent contact un der conditions such` Athat isomerization consti 10 tem. The unreacted hydrocarbons so obtained tutes the principal reaction. are returned to the lower portion of the tower, preferably at a temperature suiîlciently elevated More speciñcally the invention involves effect so as to provide the necessary reboiling action ing the isomerization reaction in a packed tower in the bottom of the tower whereby substantial or preferably a bubble tray type of tower having provision for the continuous recycling of the 15 vaporization of hydrocarbons within the tower liquid catalyst through the tower. The liquid catalyst advantageously comprises a catalyst such is eiîected. ` ' 3 l The temperature at the top of the tower may be controlled by cooling as, for example, by re as a metallic halide-hydrocarbon complex which is of greater specific gravity than the hydrocar turn of part of the isomerized stream as a re bons undergoing conversion. 20 ñuX. » In short, the operation involves effecting sub The invention has particular application to the stantially simultaneous isomerization of the feed isomerization of saturated gasoline hydrocarbons hydrocarbon and fractionation between reacted such as normal `pentane, hexane and heptane, al and unreacted hydrocarbons. The hydrocarbons though it may be appplied to other hydrocarbons including normal butane. ì 25 in passing through the tower‘are thus subjected In accordance with the invention the reaction is carried out in a packed tower advantageously repeatedly to alternate` vaporization and con of the bubble tray type. The feed hydrocarbon One advantage ofthe invention, as practiced in a bubble tower reactor, resides in realizing highly effective contact between the liquid‘cata densation. such as normal pentane is continuously intro duced to the lower portion of the tower, while a stream of catalyst such as aluminum halide-hy drocarbon complex is continuously introduced to the upper portion thereof. Conditions of tern l Y lyst and liquid hydrocarbons undergoing treat perature and pressure are maintained within the ment on each tray since the vaporized hydrocar bons are caused to bubble through the liquid hy drocarbons and liquid catalyst under conditions tower such that substantial vaporization of the such that `substantial agitation with consequent hydrocarbon occurs causing the vaporized hydro carbon to rise countercurrently to the descend ing complex catalyst. Contact between the hy thorough mixing fis realized. drocarbons undergoing conversion and the cata lyst is effected in the presence of afsuitable pro " ` ' Thus, on each tray'there> are substantial quan tities of two liquids, i. e., liquid catalyst and liquid hydrocarbons, both of which overiiow from tray 40 to tray. ` In the quiescent state the normal tend moter such as a hydrogen halide under conditions ency is for these liquids to stratify into layers due such that isomerization constitutes the principal reaction. Moreover, operation of the tower is controlled to the difference in their specinc gravities~ How- y sothat a stream is continuously withdrawn from the top> or upper portion of the tower which con tinual mixing between the liquid hydrocarbons and liquid catalyst on each tray. Consequently the isomerization for the most part involves ever,. the passage- of vaporized- hydrocarbons through the bubble caps on each tray effects con sists essentially of the isomerized hydrocarbon. Liquid catalyst accumulating in the bottom of isomerization _of the hydrocarbons while in -the the tower is continuously withdrawn and re cycled at least in part to the upper portion of 50 " i, ' ~ ‘ ` ‘ . for` a separation of reacted hydrocarbons from `unre A acted hydrocarbons;` means for obtaining `from catalyst phase and a liquid hydrocarbon phase, the latter comprising mainly unreacted hydro phase’. Other advantages include . provision unitary operation' for eiîecting isomeriza'tion and the tower. Provision is also contemplated for accumu lating in the bottom portion of the tower both a liquid the reaction .tower a stream of treated yhydro 55 carbons consisting essentially of the desired, angela 3 4 Aromatic constituents should be reduced to not isomerized hydrocarbons; and provision for con tinuous removal from the reaction zone of higher more than a fraction of a per cent or at most boiling hydrocarbons that may be formed in the reaction, such material being removed substan tially as rapidly as formed and thereby material ly reducing catalyst deterioration that would to about 2 or 3% by weight of the feed hydrocar tion unless more elevated temperatures are em otherwise occur. ployed. In certain instances it may bedesirable l _ bon since the presence of even this amount exerts an inhibiting eifect upon the isomerization reac , Moreover, byfem'plo'ying the principle of coun ter-current contact between liquid catalyst and to maintain a limited amount of aromatic ma terial in the reaction carrying out the reaction at more elevated temperatures so that substan tial isomerization is obtained. It has been found hydrocarbons undergoing treatment it is possible to carry out the conversion reaction under con ditions which more closely approach realizing the that undercertain conditions, the presence of maximum equilibrium concentration of isomerized such a small amount of aromatic material may Y hydrocarbons witho-ut encountering excessive permit carrying out the isomerization reaction at cracking and other undesired sideA reactions. The temperature gradient, which exists through the tower, favors maximum conversion since the higher temperatures without realizing excessive cracking. In ‘this connection anradvantageous vcracking, inhibitorjcomprises naphthene hydro carbons such as cyclopentanes, cyclohexanes and temperature decreases upwardly through the cycloheptanes. It has been found, for example, f tower.. A lower temperature near the Vpoint of catalyst introduction to the reaction zone permits 20 that normal pentane may be isomerized with an maximum equilibrium concentration of the iso aluminum halide type of catalyst at temperatures parafiin in the products leaving the reaction zone. in the range 160 to 200° F. without substantial cracking occurring when the reaction Vis carried Mention has valready been made of a metallic halide-hydrocarbon complex as one example of a suitable catalyst. It is contemplated that such complex be sub stantially free from undissolved solid metallic halide. A desirable’ catalyst comprises aluminum out in the presence of about 10% or so of cyclo 25 hexane by weight of the normal pentane undergo ing conversion. ' Therefore, one modification of the presentA in vention involves effecting the reaction in the pres halide-hydrocarbon complex of such character ence of a suitable cracking inhibitor'such as a that> when a minor portion of theV complex is 30' low boiling naphthene hydrocarbon. In order to describe the invention in more de mixed with a. major portion of lWater the hea-t evolved from vthe mixture amounts to‘about 200 to tail reference will now be made‘to the ‘accom panying drawing comprising a flow diagram illus 400 and preferably about 300> to 320 calories per gram of catalyst. trating one mode of practicing the invention. For convenience this liberated heatA may be « referred to as the “heat of hydrolysis.” This is ` Referring to the drawing a feed hydrocarbon such as normal pentane is conducted" from a source not shown through a pipe I to a lower por determined, for example, by breaking an ampoule containing a weighed amount of complex, for example, about 3 grams in a weighed quantity tion of a reactor 2. flask or calorimeter initially at about normal room may be of more or less conventional design hav ing risers and caps so that a substantial depth of ` ' The reactor 2 advantageously comprises-a tower of water about 300 grams contained in a thermos 40 packed with bubble trays 3. The bubble trays temperature. The mixture is stirred and the rise in temperature measured.> From this rise in tem perature the heat’liberated is calculated as cal ories per gram of complex. The complex may 45 be prepared by reacting aluminum chloride with kerosene or gasoline hydrocarbons, aliphatic hy drocarbons in general being preferred. The re action is effected in the presence of hydrogen liquid comprising both catalyst andhydr'ocarbons, may be maintained upon each tray, through which liquid rising vapors are caused to bubble as they p-ass upwardly through the tower thereby effect ing the previously describedmixing between cata lyst and liquid hydrocarbons. ' »Advantageously a substantial space is provided chloride or other halide. For example, 1000 parts 50 in the bottom portion of the tower within which to accumulate liquid descending through the tower and to which‘reference will be made later. The catalyst in the form of a liquid complex substantially free from undissolved solid mate by weight of anhydrous aluminum chloride pow derr is mixed with about 1630 parts by weight of kerosene derived from mixed base crude. This mixture Vtogether with 50 parts of hydrogen chloride is charged to a closed reactor and agi rial is introduced to the upper portion ofthe tated for about 4 hours at a Vtemperature of about 210° F. The reaction mixture is thereafter cooled and the contents removed and separated into tower through a pipe 4. Fresh catalyst from ~ ` ' ' ay source not ’ shown may be introduced continuously or intermittentlyl phases. The complex phase is removed from the through a pipe 5 which communicates with the previously mentioned pipe 4, Other meansI of hydrocarbon phase and this complex comprises the liquid complex catalyst. introducing fresh catalyst may be employed s_uch While mention has thus been made of alumi as in solution in a portion of the feed hydro num chloride in preparing the complex never carbon. theless it is contemplated that other metallic halides including aluminum bromide may be em ployed. . , " introduction contains a‘quantity of catalyst liquid' and hydrocarbon liquid,V the surplus overflowing' In the practice of the invention it is desirable which may react with the catalyst causing cata from an upper tray to a lower tray and eventually arriving in the settling space at the bottom of the 70 tower. lyst" deterioration or which may otherwise react to form undesired compounds. Such preliminary treatment-may include acid treatment or solvent extraction. Oleiins may be removed' by' poly merization. ' ' ' ' of the bubble trays below the' point of 'catalyst' ' to purifyv the feed hydrocarbons to remove oleflnic and aromatic constituents and other materials ' In actual operation, as already described, each 'I'he tower is maintained under conditions of temperature and pressure so that vaporizationv of hydrocarbon occurs within the tower, thev va 7.5 porized Vhydrocarbons rising upwardly'throughV the succeeding trays. Liquefied hydrocarbons 52,404,649r 6 5 through' a pipe I6 to an extractor I'I wherein the hydrocarbon‘mixture is subjected to contact with overñ'ow from tray to tray along with the catalyst and likewiseaccumulate in the lower portion of the tower. „ . Y a suitable selective solvent. o When charging normal pentane to theA reactor the hydrocarbons collecting in the top of the tower will comprise essentially isopentane which is substantially lower boiling than normal pen tane; Normal pentane will accumulate in the ` . This solvent is one which has preferential sol’ vent action upon naphthenic constituents and thus exerts selective solvent action as between naphthenes and paratlins. Suitable examples of a selective solvent com prise furfural, phenol, -nitrobenzene, sulfur di molecular weight material which may be formed 10 oxide, etc. The resulting raffinate phase comprising paraf during the reaction. ñn hydrocarbons and some solvent is discharged Thus, in the bottom portion of the „tower there through agpipe I8 for such further treatment as will accumulatetwo phases, namely a catalyst may be desired including recovery of the solvent phase and a hydrocarbon phase. `The catalyst phase is drawn oiï from the bottom of the tower 15 therefrom. The extract phase comprising the main body-ofthe solvent with the naphthene hy through a pipe S. `All or a portion thereof is con drocarbons dissolved therein is drawn off through ducted through a branch pipe ‘I which commu a pipe I9 to a suitable solvent recovery unit 29 nicatesV with the previously mentioned pipe 4 and wherein the solvent is removed from the naph through which latter the withdrawn complex is thene hydrocarbons, returned to the tower. u The recovered naphthene hydrocarbons are The hydrocarbon phase is continuously drawn bottom portion of the tower as well as any higher off through a pipe 8 and all or in part conducted to a fractionator or stripper 9 wherein the `un reacted feed hydrocarbon constituents are stripped or separated therefrom, the remainder or residue comprising the previously mentioned higher molecular weight material. conducted all or in part through a pipe 2I which communicates with the previously mentioned pipe 4. In this way the recovered naphthene hydrocarbon is returned to the reaction zone to serve as `an inhibitor of cracking in the conver~ sion of freshl‘feed hydrocarbon. ' The isoparaflin which accumulatesin the top The fraction comprising unreacted hydrocar bons is then _recycled through a pipe Iû to the lower portion of the reactor preferably at a point above that at which it was withdrawn but below the point at which fresh feed is being introduced to the tower. The amount of hydrocarbons so portion Yof the »tower is continuously withdrawn through a pipe 22 communicating with a con denser and cooler 23. From the condenserI 23' the liquefied hydrocarbons pass to a receiver 24. Gaseous constituents may be released through a pipe 25. A portion of the isoparañin accumulat recycled and the temperature at which it is `_re ing in the receiver 24 may be recycled through a cycled, being such as to supply a substantial 35 pipe 2B to the upper portion of the reactor 2 to amount of heat to the bottom portion of the provide reñux cooling therein. tower thereby causing substantial vaporization The amount so refluxed will depend to a large within the tower. These hydrocarbons may be extent upon the amount of heat being added at recycled in vapor form. As indicated in the drawing the promoter such 40 the bottom of the tower. Isoparafñn hydrocarbons not so refluxed to the as hydrogen chloride may be continually added top of the tower are continuously discharged from a source not shown through pipes II and through a pipe 21. I2 communicating with the previously mentioned The `specific procedure described above for pipes I and II). In this way the promoter may be treating the hydrocarbon phase withdrawn from 45 introduced to the reaction zone. Other means of the tower through the pipe 8 may vary consid injecting `the promoter to the reaction zone `may be employed. , The residual fraction of the withdrawn hydro carbon phase may b-e discharged from the bottom of the fractionator 9 through a pipe I3. When the hydrocarbon phase withdrawn through the pipe 8 is substantially free from higher molecular‘weight material it may be re cycled without the above-described fractionation but after heating suniciently to supply the re quired amount of vaporization in the bottom por tion of the reactor. On the other hand when the reaction is being erably; for example, azeotropicfjdistillation may be resorted to for the purpose of separating naph thenes from parañins. `, . It will be realized that in operating the reac tor 2 a temperature differential will exist between thetop and bottom _thereof which may be of the order of aboutlO to 50° F. ' u ` ‘ The point at which the recycled complex is re turned to the reactor may be varied as desired but usually it is advantageous to return it to the tower at a point where the concentration of the ‘isomerized hydrocarbon' in the reaction mixture is equal to or less than the'equilibrium concentra eiîected in the presence of an added naphthene hydrocarbon it Vis desirable to subject the with 60 tion. In other words, if it is introduced at a point at which the concentration is greater than drawn hydrocarbon phase to additional treating the equilibrium concentration reversion reactions steps, so that the naphthene may be segregated Vrnay occur. ‘ therefrom to permit its return to the upper por tion of the reactor. ` While mention has been made of applying the Thus, the residual fraction drawn off from the 65 process to normally liquid hydrocarbons, never theless it is also contemplated that it may be ap fractionator 9 through pipe I3 may be conducted plied to the isomerization of normal butane. In all or in part through a pipe I4 to another frac- ' tionator I5 wherein the residual hydrocarbon> mixture may be separated into a light fraction comprising the naphthene hydrocarbons `and hy . isomerizing normal butane the> reaction may be carried out under a pressure of 250 pounds and at an average temperature of about 210° F. ob drocarbons boiling within the same range but which may have been formed* in the isomeriza taining a distillate fraction overhead through the tion reaction, and a heavier fraction. morel of isobutane. ` The heavier fraction is discharged from theî pipe- 22 which may comprise as much as 98% or The process is particularly applicable to the system while the light fraction maybe conducted 7,5 treatment 0f; individual hydrßßarbßne auch as attrici-cf> 7 8 . normal butano, normal pentane, normal hexane', etc., rather than mixtures composed ‘of hydrocar-V bubble trays, ‘continuously introducing> catalyst complexto the upper portion of said tower, ‘said complex liquid being substantially free from un-. dissolved solid aluminum halide continuously in troducing feed hydrocarbon to the lowerrportion bons of different molecular weights'. In speaking of individual hydrocarbons, it is, of course, con templated that the feed may Ycomprise petroleum or hydrocarbon fractions consisting essentially of of said tower, supplyi-ngheat tothe lower `por the individual hydrocarbon or as in the case of a tion of said tower sumcient to :effect fractiona-v Cs or Cv fraction‘consisting essentially of a mix~ tion within the `to‘wer'between reacted andrunre acted hydrocarbons, continuously withdrawing ture of hydrocarbons having the same number of carbon atoms per molecule. V reacted feed hydrocarbons in vapor form from the l Reaction temperatures and pressures will de top of saidtower said hydrocarbons consisting essentially of isomerized hydrocarbons, continu pend upon the natureY of the feed undergoing treatment. Where the feed consists essentially ously withdrawing catalyst complex from the bot of normal butane a reaction temperature of aboutl 200 to 220° li". is advantageous With higher mo tom of said towerfrecycling withdrawn complex lecular weight hydrocarbons correspondingly low~ contact between descending complex and rising` to the upper portion of said tower, and effecting er temperatures are.” employed unless the reac tion is yeffected in the presence- of an ßinhibitor such as nap‘hthene hydrocarbons. 4In such case hydrocarbons such as. normal pentane, normal hydrocarbons‘w'ithin the tower in the presence of Y hydrogen halide under conditions such that isom- i erization constitutes the principal reaction. 5.'A process for isomerizing saturated hydro~ hexane, etc., vmay be isomerized at temperatures carbons by contact with an isomerization catalyst i which arev also in the range about 200 to 250°?. While specific mention of metallic halide-'hy drocarbon complexes as catalysts has been made, consisting essentially of aluminum halide-hydro-V carbon complex liquid, which comprises effecting the reaction ina bubble tray tower, passingihy it is intended that other liquid isomei‘ization cata ., drocarbons ’undergoing conversion upwardly lysts may be employed, which areI heavier‘than through said tower countercurre'ntly'to descend the hydrocarbons 'undergoing treatment and ing catalyst under conditions such that isomer- ‘ which are substantially immiscible therewith un ization constitutes the principal reaction, said der the conditions prevailing within the reaction complex being substantially free from undissolved ZOIle. . . y Obviously many modifications andyariations of the invention as above set forth may be made Without departing from the spirit'a'nd scope there of, and therefore only such limitationsV should be .it solid aluminum halide and characterized by hav ing a heat of hydrolysis in the rangeY 200 to' 400 calories per gram of complex, introducing feed hydrocarbon to a lower portion of> said- tower,- accumulating in said tower below the point of ' imposed as are indicated in the appended claims. "" feed hydrocarbon introduction a liquid catalyst I claim: ' _ phase and a liquid hydrocarbon phase, separately l. A process for isomeriz'ing saturated hydro carbons by contact, in the presence of hydrogen halide, with an isomerization catalyst consisting withdrawing said phases from the tower, recy undergoing conversion through a reaction zone countercurrently to a body of said complex cata hydrocarbon phase, returning the heated hydro cling withdrawn catalyst phase to‘ the upper por tion of the tower at a point substantially above essentially of aluminum halide-hydrocarbon com 40 that at which feed hydrocarbon is introduced, plex liquid which comprises passing hydrocarbon vaporizing at least a portion of said withdrawn lyst substantially freefrom undissolved solid alu minum halide and characterized by having a heat lof hydrolysis'in ,the îrange 200 to 400 calories per gram of complèn'ïsubjecting hydrocarbons pass ing through said Zone' repeatedly to alternate vaporization and condensation while in contact with the catalyst, continuously removing from lsaid zone a treated hydrocarbon stream consistm carbon phase to the tower at a point below that' at which feed hydrocarbons are introduced in such amount. and at suihcientetempe‘rature to cause substantial vapor’iZat-ion of hydrocarbons withinl the tower'and' controlling the ,tempera ture at the top of said tower to remove’ continu ously a stream` consisting essentially of isomer ed ized hydrocarbons. ' 6. A processV for isomerizing normal par'ailin ing essentially of isomerized hydrocarbons, sepa ratcly withdrawing complex catalyst after contact with entering feed and and returning withdrawn Íhydrocarbons having 4 to '7 carbon atoms and normally `free from naphthenic hydrocarbons by catalyst to the reaction. zone at a point in closer ' essentially of aluminum chloride-hydrocarbon proximity to the point. of discharge from the re action zone for isomerized hydrocarbons. 2. The methodaccording to claim 1 in which the catalyst comprises aluminum chloride-hydro'-` carbon complex. u 3. The_method according to claim> 1 in- which the catalyst comprises an aluminum chloride hydrocarbon complex and is of such character’> that when a minor portion `thereof is mixed with a major> portion of Vwater the heat evolved amounts to from. about 300 to 320 calories per contact with an isomerization catalyst consisting complex liquid, which comprises effecting the ré action in a bubble tray tower, passinghydrocar bons undergoing conversion upwardly through said'tfower countercurrently to descending cata 60 lyst- under conditions such that isomerization >constitutes th‘eprincipal reaction, said catalyst 'eing' substantially free from _undissolved solid aiuminum halide and having a heat of. hydrolysis of aboutSOO to 320 _calories pergram of complex, introducing feed hydrocarbon to a lower portion of 'saidtowen accumulating in said Vtower- below gram of complex, said complex being substan theV` point of. feed hydrocarbon introduction a liq? tially free` from» undissolved solid` aluminum uidV catalyst. phase and a liquid hydrocarbon halide. phase, >said hydrocarbon phaseV comprising unre 4. A process for isomerizing saturated hydro 7.0 acted hydrocarbons and' higher boiling hydrocar carbons by Contact with an isomerizationcatalyst bons, separately withdrawing said phases, recy consisting essentially of aluminum halide-«hydro cling withdrawn catalyst phase to the upper por_» carbon complex liquid which comprises continu tion of the tower at a pointsubstantially above ously Y.passing hydrocarbons undergoing conver that at which feed hydrocarbon is introduced, sion through a Vertical reaction tower containing 75 separating from said withdrawn hydrocarbon 2,404,649 9 10 phase a fraction consisting essentially of unre feed hydrocarbon introduction, vaporizing from acted paraffin hydrocarbons. vaporizing said frac tion, returning the vaporized fraction to the tower the withdrawn hydrocarbon phase unreacted nor mal paraiiin hydrocarbons, leaving a residual hy drocarbon phase, returning the vaporized hydro at a point below the point of feed introduction in such amount and at sufficient temperature to cause substantial vaporization of hydrocarbons within the tower and controlling the temperature at the top of said tower to remove continuously a stream consisting essentially of isomerized hy drocarbons. . carbons to said tower at a point below the point of feed hydrocarbon introduction in such amount and at such a temperature as to cause substan tial vaporization of hydrocarbons within the tower, separating naphthene hydrocarbons from said residual hydrocarbon phase, returning so separated naphthene hydrocarbons to the upper portion of said tower and controlling the tem 7. The method according to claim 5 in which the isomerization reaction is effected in the pres perature at the top of said tower to remove con ence of a small amount of added naphthene hy tinuously a stream consisting essentially of isom drocarbon. y 8. A process for isomerizing normal parañin 15 erized hydrocarbons. 9. The process according to claim 8 in which hydrocarbons having from 4 to 7 carbon atoms the recycled naphthene hydrocarbons are com per molecule and normally free from naphthenic mingled with recycled catalyst phase prior to re hydrocarbons by contact with an isomerization turnto the upper portion of the tower. catalyst consisting essentially of aluminum chlo l0. A process for isomerizing saturated hydro ride-hydrocarbon complex which comprises ef 20 carbons which comprises passing hydrocarbons fecting the reaction in a bubble tray tower, pass undergoing conversion through a packed reaction ing hydrocarbons undergoing conversion upward tower countercurrently to a body of isomeriza ly through said tower countercurrently to de tion catalyst consisting essentially of aluminum scending complex liquid in the presence of hy drogen halide and under conditions such that 25 chloride-hydrocarbon complex and substantially free from undissolved solid aluminum chloride, isomerization constitutes the principal reaction, subjecting hydrocarbons passing through said said complex being substantially free from un tower repeatedly to alternate Vaporization and dissolved solid aluminum chloride and charac condensation while in contact with the catalyst, terized by having a heat of hydrolysis of about 300 to 320 calories per gram of complex eifecting 30 effecting said contact in ther presence of hydro gen halide under conditions such that isomeriza the reaction in the presence of a small amount tion constitutes the principal conversion reaction, of added naphthene hydrocarbon higher boiling removing overhead from said tower a stream con than the paraffin hydrocarbon undergoing treat sisting essentially of isomerized hydrocarbons, ment, introducing feed hydrocarbon to the lower portion of said tower, accumulating in the bot 35 separately withdrawing complex catalyst from the lower portion of said tower, recycling withdrawn tom portion oi said tower a liquid catalyst phase complex to the upper portion of said tower, in troducing saturated feed hydrocarbons to the reacted feed hydrocarbons, said naphthene hy portion of the tower at a point intermediate the drocarbon and higher boiling hydrocarbons, sepa rately withdrawing said phases, recycling with 40 points of complex withdrawal from and return to and a liquid hydrocarbon phase comprising un drawn catalyst phase to the upper portion of said tower at a point substantially above the point of the tower. MAX NEUHAUS.