Oct. 15, 1946. - C, R, RINGHAM _ ALKYLATION PRocEs’s- Filed Sept. 28, 1944 ì 2,409,389 ' \ y 2,409,389 Patented Oct. 15, 1946 UNITED V STATES PATENT ¥ ` OFFICE ,N Clarence R. Bingham, Oklahoma. City1 Okla., `as ksignor to Phillips Petroleum Company, a corpo ration of Delaware npplicationseptember 28, 1944', .Se'rlal‘Na 556,208 s claims. (o1. ctc-csail , `This `invention relates tothe conversion of hy drocarbons in the presence of aluminum vhalide catalysts. In particulary embodiments it relates to -aikylation of alkylatable.hydrocarbons- by `re , 2 presence of aluminum halidecatalysts one of the mîdlàjor` products -is diisopropyl, although struc turally this >product is not “ethyl isobutane” even though it is a hexane. However, in many in action 'with alkylating reactants in the presence 5 stances structural addition products are obtained, of _liquid hydrocarbon-aluminum halide com-' as. when ethylene reacts with benzene to form plexes as catalysts. In one specific vembodiment l ethylbenzene or when isopropyl alcohol or an iso propyl` halide reacts with benzene to form iso it relatesto the reaction of isobutane and ethyl ene toproducediisopropyl.` ~ , _ prop_ylbenzene. The commercial practice of suchY alkylation Aluminum halide catalysts have been used in 10 processes presents `numerous problems which are numerous processes for the conversion of hydro not ,found in laboratory operation and which carbons,l including decomposition or cracking of higli-boiling hydrocarbons, isomerization of low often cannot be foreseen. on the basis of results boiling hydrocarbons, and alkylation ci alkylat» able hydrocarbons, including both isoparafl‘ins, ‘normal para?lins, ,cycloparaiïins and aromatic obtained in laboratory runs.` ‘Y One of the :great est diuîculties experienced in commercial opera tions is the efficient use of equipment while se hydrocarbons. In such processes these catalysts ` curing, atthe same time, uniform operation over an extended period of time. It is particularly im have been used as such,_suspended inor dissolved portant to have uniform catalyst activity >during in a reaction mixture, suspended on solid supports such asactive carbon, Activated Alumina or alu 20 an extended period of operation, such as one last ing for several Weeks, in order that uniform vol minous‘materials such as bauxite, active silica, umesìiof materials may be treated and uniform and various clays such as fuller’s earth, kiesel reaction efliuents may be available for treatment guhr, etc., >and 4as separate liquids _in the form oi' complexes with organic and inorganic compound-s, in separating equipment having a fixed size and The more usefulof the liquid complexes are those 25 operated `at maximum eiiiciency. I `have found formed With `parailîln'ic hydrocarbons, lespecially >those formed with more »or lesshighly lbranched normallyv liquid paramn hydrocarbons boiling in the `boiling ranges of those fractions’generally identi-ned asgasoline and kerosene. In many in-v stances i-t is desirable to have present» a small amount of :a hydrogen halideJ sometimes `cnly about 0.1 to about l to 5 perrcent by Weight». This that an aluminum halide-hydrocarbon complex maybe used as a catalyst in commercial opera tions- for the alkylation of hydrocarbons and sat isiactorzily> uniform catalyst activity may be es tablished and maintained, and at the same time a number of. relatively small reactors may be used to treat large quantities o_f material, by the spe ciiic method of combining groups of reactors and catalyst settlers, and by combining all of the material may be present _as aresult of side=reactions, such as when water is present in a charge (1': 01 used catalyst before itis returned back to the individual reactors, in a Vmanner which will be stock, when an organic halogen compound is more `fully and completely disclosed in connection present in a charge stock, when some interreac tionvbetiveen the aluminum halide and hydro carbon takes» place, or when a hydrogen halide isy with the accompanying drawing. catalysts` are often conducted without` theÍ knowl edge or appreciation that'minor amountsîof >a hy~ drocarbon andanvalkylating reactant in a ,con ` Y An object .ofthis invention is to convert hydro deliberately added. , ySince itisysubstantially lim 40 carbons in the presence of a `hydrocarbon-alu» minum halide complex catalyst. possible to effect complete. dehydration ofVV all Another object of this invention is to effect an equipment andmaterials, especially in acommer cial process, conversions with aluminumhalide Valkylation reaction between an alkylatable- hy drogen halidearepresent. _' .¿ .. f As _alkylating reactants vfor »use in alhylation processes -for reaction with-alkylatable hydrocar bons low-boilingoleñ-ns are generally used` VHow ever, other alliiylating` reactants have` also been proposed- such as alkyl halides and alcohols. tinuous commercial process. Still another. object Ofthis invention is to ób tain. uniform reaction. in an alkylation process Whileat the same time using a large number of relativelyfsmall reactors'. Still another object of this invention is to re act isobutane and ethylene to produce high yields Otten the -products of the alkylation Will not -re Otherobjects and advantages .of this invention sult from structural addition'of the alkylating‘re will become apparent, to `one skilled in the art, actant to the alkylatable Ahydrocarbon. Thus, when -isobutane is. reacted with ethylene. in „then 55 from the »accompanying disclosure and discussion. of diisopropyl. . . n \ 2,409,389 3 A preferred embodiment of my invention will now be discussed in some detail in connection with the accompanying drawing which forms a part of this application, and which shows an arrange ment of apparatus suitable for practicing the in vention. While various features of the invention will be discussed in connection with the reaction of isobutane and ethylene to produce diisopropyl in the presence of a liquid aluminum chloride hydrocarbon complex as the catalyst, it is to be understood that the invention can be applied tov other reactants and to other liquid catalysts. Referring now to the drawing, an isobutane stream is passed to the process through pipe I0 and a mixture of isobutane and ethylene is passed to the process through pipe I I. AS will be appre ciated by those skilled in the art in-a commercial 4 and with a hydrocarbon to catalyst ratio within the reactor of 3:2 and a flow rate of 1.25 gallons of alkylate per gallon of catalyst per hour, the ñow rate of alkylate should be such that 500 gallons of alkylate are produced per hour. The catalyst itself is substantially insoluble in hydrocarbons and hydrocarbons are not substan tially soluble in it. It is preferred to have a vol ume ratio of hydrocarbons to catalyst in the reaction zone between about 9:1 and about 1:1 and the preferred ratio has been found to be about 3:2. When the reaction mixture is main~ tained intimately admixed with the catalyst under the preferred conditions the hydrocarbon phaseis the continuous phase. Under these con ditions the catalyst readily separates from the a hydrocarbons and power requirements in order to maintain a suitable intimate admixture are by comparatively small amounts of other hydro- ‘ not excessive. However, when a greater amount carbons. Such hydrocarbons, however, should be 20 of catalyst is used, it has been found that a phase present in relatively small amounts, particularly inversion may take place with the result that the when they are also reactive under the reaction catalyst phase is the continuous phase and the plant these hydrocarbons will be accompanied conditions. One rather typical composition for c_ach of these streams will be presented in the specific example given hereinafter. The alkyla tion reaction is conducted in four reactors-I2, I3,`I4, and i5-with reactors I2 and I3 being operated in series and reactors I4 and I5 being operated in series, the first said set of reactors being operated in parallel to the second set of reactors. More than two such sets of reactors may, of course, be used if desired. Contents of each reactor are intimately admixed by means of a stirrer 20. The isobutane stream is passed through pipes _i6 and I'l in two portions to the bottom of each of reactors I2 and I4, which are the primary reactors in each set. A catalyst stream from a common catalyst source, such as pipe 2l, is passed in two portions through pipes 22 and> 23 to the bottoms of reactors I2 and I4. This catalyst stream comprises used and fresh catalyst as will be more thoroughly discussed hydrocarbon phase the discontinuous phase, which is not nearly so satisfactory. Under such conditions it is quite difficult to obtain adequate physical separation between the hydrocarbon phase and the catalyst phase and a considerable amount of power is required in order to ade quately mix hydrocarbons and catalyst charged to the reaction zone. As the mixture of reactants and catalyst passes up through the primary reactors it is thoroughly admixed so that the catalyst is present in ex tremely small particles. From the top of each of the primary reactors this intimate admixture is passed, through pipes v33 and 34, to the bottom of the corresponding secondary reactor. At this point the final two portions of the isobutane ethylene mixture arev added, through pipes 35 and 36. rThe hydrocarbon-catalyst mixture is also intimately admixed in the secondary reactors I3'and I5 to effect suitable reaction. The result ing admixtures are passed through pipes 31 and 38 to corresponding primary settlers 40 and 4I. hereinafter. The isobutane-ethylene stream is split into six portions. To the bottom of each of the primary reactors I2 and I4 is added one 45 These settlers are preferably vessels set on a slope of these portions through pipes 24 and 25. To the with a solid bafiie plate 42 and 43 near the inlet middle of each of the two primary reactors I2 and and extending about halfway up in the tank. I4 is added another portion through pipe 26 and This baffle plate serves to distribute the incoming 2ï. A recycled portion of the hydrocarbon efflu emulsion across the tank section, thereby tending ents of the reaction is passed throughA pipe 30 50 to reduce the short-circuiting eiïect,` and also and divided into two portions which are passed serves as a retainer wall for the catalyst which through pipes 3| and 32, each portion also being settles out. The liquid catalyst which settles out added to the bottom of the primary reactors I2 is removed through pipes 44 and 45 and combined . to form a common catalyst source in pipe 2|. " A preferred reaction temperature for this con A pipe 39 is provided joining efliuent pipes 31 and and I4. version is between about 50 and about 200° F., 38 for use in case of emergency if one of the set-` preferably about 80 to about 150° F. When alkyl tling tanks 40 or 4I needs to be taken out of ating hydrocarbons the activity of the catalyst service. Ordinarily this` pipe 39 will not be used. herein described is sufficiently high that even From the top part yof settling tanks 40 and 4I ethylene undergoes rapid reaction within this 60 a hydrocarbon mixture is passed through pipes temperature range. Itis generally preferred to 46 and 4i and is combined in pipe 50. A sub operate under a pressure such that the hydro stantial >portion of this combined hydrocarbon carbons are present in the reaction Zone substan material is passed through pipe 5I to cooler 52 tially in liquid phase and in many instances the and is returned to the reactors through pipe 30 hydrocarbon material will be kept in completely as previously discussed. Since this combined liquid phase under the preferred reaction condi hydrocarbon material still contains a small tions. The flow rate of reactants to the reaction amount of entrained catalyst, generally, however, not more »than about two or'three to about eight zone is preferably expressed in terms of amount or ten per cent of the total catalyst, the remain of product produced, and when reacting isobutane ing portion is passed to a secondary settler 53. with ethylene to produce diisopropyl I prefer to operate at flow rates between about 0.2 and about Since the catalyst which is still present in the 1.5 gallons of total alkylate produced per gallon hydrocarbon material is quiteñnely divided and of catalyst present in the reactor per hour. Thus, represents the finely divided particles present in when reacting isobutane and ethylene in a reactor the emulsion passed from the secondary vreactors having 'a total internal volume of 1,000 gallons 75 through pipes 31 land 38, a >somewhat longer» seti 2,409,389 6 tling time is necessary in settler 5.3 than was‘used cent .by‘weight-of `aluminum chloride, isa fluid in either settlers door 4|. Catalyst `whichr‘sepa=~ ture with the catalyst removed through pipes l44 red-brown oil' having `a viscosity less `than `200 c'entistokes at 100° F., and is used as theactual catalyst. v'The»high-aluminum chloride typecan and l5. be `added during a continuous ‘ run» in> :small rates out ispassed through pipe `5t ‘for admix-` ' ^ ` ,i i p ’ A liquid hydrocarbon material substantially free from catalyst and containing unreacted hydrocarbons andalkylate is passed` from settler »53 thro-ugh pipe 55 toïseparating means »60. Gen erally it will ber desirable to wash this hydro carbon material with an' alkaline solution, to amounts tol-the recirculated» catalyst‘inorder to maintain Acatalyst activity. i Catalyst s activity, however,` can “be maintained in other ways, >as: by adding aluminum halide directly to `recirculated catalyst or by dissolving aluminum halidein one of the streams charged to the reaction zone. The liquid complex should not lie-‘contaminated with remove any Vacidic materials which may be pres water or other reactive, oxygen-containingk com ent, before the material »is subjected to fractional pounds. ' distillation. A diisopropyl fraction is Aseparated In‘making the original batch of catalyst 'kero and removed through pipe `62 las a product ofthe 15 sene ` or other hydrocarbon may be added-through process. ’Unreacted isobutane is separated and pipe 10 to a catalyst preparation vessel ’Hand returned tothe process through pipe 63.- 'Normal an aluminum halide such _as aluminum` chloride butano, which will include that initially accom* panying the‘char-ge »stock- and any normal ïbutane may be added through pipe 12. These materials formed byisomerization :during `the alkylation 20 may be intimately admixed by means of a stirring process, `may be separated and discharged through mechanism 13. After the process has been `start pipe 64. One or more other alkylate fraction may also be recovered, as through pipe 65. `Any undesired light gases may be discharged through pipeßß. - i v ‘ ed the activity of the recirculated catalyst `may be 'maintained by passing a‘ portion of the recir culated catalyst through pipe 'M to Vessel “ll 25 wherein aluminum chloride, 'either as such vOras-a Aluminum chloride ‘is the halide which will most generally be used in ythe »practice of my invention althoughit is Anot outside of the broad high-aluminum chloride complex `such as previ hydrous aluminum halidewiith `a paranin hydro carbon, or paraflinic hydrocarbon fraction, at terial may be added through either of pipes 10 or 112. In such instances it is often not neces sary to add` hydrogen halide to the reaction sys tem. However, if it is found desirable at. any ously discussed, may be intimately _mixed 'with it. The resulting fortified catalyst is passed through pipe 'l5 Vandireturned to pipe 2|-`wherein est concepts of my invention to i use other aluminum hal-ides, particularly aluminum bro 50 it is mixed with the recirculated‘catalyst. `Since mide. While aluminum fluoride generally‘does such `treatment tends to increase the total vol urne` of catalyst available it will >generally be not givesatisfactory results, vmixed halides such found necessary to maintain 'a desired'volume of as AlClzF, AlClFz, AlBraF, and the like, `may-often be usedv successfully» Liquid hydrocarbonsalu catalyst by withdrawal of material from pipe“ minum halide catalysts are. generally’ prepared `through pipe 16. 'When it 'is desired to usel a hy drogen halide in preparing the catalyst suchma by reacting a relatively pure and substantially an ~al temperature between about 1510 «and» about 230° F. Usually, butnot always, it isidesirable to .ef lrect thelproduction of the Acatalystbytadding dur ingits tori-nation Aa small amount of a hydrogen time to add a hydrogen vhalide to the reaction system, any desired portion may' be added halide and to lmiX' vigorously the hydrocarbon through pipe 1T! lto the catalyst present in pipe 2 i. `and 4alur-n-inurn halide until the ‘ resulting .complex By maintaining total emulsincation in all of >the reactors in such a catalytic alkylation proc contains .in »combination from about 5G to about T0 per »cent by weight of aluminum halide. fSatis factory fluid complexes have-been prepared from fav-ariety of paraffin hydrocarbons'including nor mal heptane, isooctane, »a parañinic .alkylate‘ l`.frac~ tion resulting from reaction »of isobutane and butylenes, and boiling `above 350” F., an oleflnic polymer fraction ï'boiiing- i-nV the upper part :of the gasoline range, and kerosine. nnr essential re-- fquirement for the» preparationof agood catalyst -appears to be the use of a-»suiiiciently powerful mixing to maintain the aluminum halide and the hydrocarbon intimate contact during the pe riod the Vcatalyst is being prepared. In the ini'. tial stage individual particles of aluminum halide ess, and allowing no settling of catalyst until.` the reactor effluents `enter the settling tanks. the catalyst phase system has been consolidated into what may be `considered a single control unit, inasmuch as the catalyst pumped back into the reactors from the settling tanks is uniform in composition. , Therefore, the level of `activity of the* catalyst phase is the same, for all practical purposes, in .all parts‘of the system at any given instant. Activity determinations may .be made on catalyst sampled at any point in the catalyst recycle system, and this will establish definitely y the condition of the catalyst >in all parts of the system. ySuch an arrangement is markedlyrdifg ’appear to become -coated with a layer of ¿sticky 60 ferent'from a system wherein each reactor and its settler are separate from ’the other .reactors and settlersfor in which a settler‘isi-madeintegral complex and if‘the mixing power is not »great `enough such particles tend to accumulate vand/'or ‘agglomerate'to form a viscousmass which settles to the bottom of thereaction vessel and-‘further formation of the desired complex> is inhibited or prevented, `since unreacted »aluminu-m‘halide no longerhas access tothe hydrocarbon phase. Two general types of catalyst have been prepared. ’These 'may be ~characterized as high-aluminum halide and low-aluminum halide types. `When preparing a catalyst with- aluminum `chloride the high-aluminum chloride type contains 80 vto 85 'per cent by weight of aluminum chloride vand is with each reactor proper with allowance "being made for return of the catalyst directly Irom‘the settler to the reactor. When any vsample `taken ‘from the system shows theV catalyst to be below the- desired activity level, a predetermined quan tity of the catalyst phase will be withdrawn from the catalyst recycle line, and an equivalent amount» of fortilied catalyst addedat that point. Catalyst withdrawal and addition may be either a batch or a continuous process. ' It Will be appreciated that the drawing vist a schematic representation oi process flow, and of *a* -yellow ‘highly viscous material'. ‘Thel low ‘aluminum chloride‘type` containsÍ about -55- per 75 equipment-whichmay be used in lconducting `my 2,409,389 8 invention upon a commercial basis. Various spe ciñc pieces of equipment such as alkylation con primary settling zone, having a sufficient size to provide a settling time vof about 5 minutes, which tactors, fractional distillation columns, pumps, control valves, heaters, coolers, 'catalyst cham cent of the dispersed catalyst. The resulting hy bers, and the like are well known to those skilled in the art and suitable equipment can be `readily assembled for any specific application of` my in vention, by one so skilled, by following the teach portion is cooled and recycled, in thevamount ings contained herein. , , e As an example of the operation of my inven tion, an isobutane feed stock is charged to the _apparatus illustrated in the drawing through pipe Ill. This stream has the composition shown in the accompanying table and is-charged in a continuous stream in the amount indicated. An isobutane-ethylene mixture is prepared by-using a liquid isobutane stream, from the same source as the isobutane feed, as an absorption liquid in is sufficient to permit removal of about 95 per drocarbon mixtures are combined, and a lmajor shown in the table. The remaining portion of thev combined mixtures passess to a secondary setling zone, which has a suñicient size to pro vide a settling time of about 30 minutes. The catalyst which settles out from each of the three settling zones is combined, a portion (about 14 volumes per day) is discharged from the system through pipe 16, another portion is passed to a catalyst make-up vessel 7l, where it is fortified by the addition of fresh solid aluminum chloride. The resulting fortified catalyst is blended with the major part of the catalyst in pipe 2I to form a demethanizer to which is charged, as a gas, an a source of catalyst supply, with a uniform cat eiliuent stream from a process for converting an 20 alyst of high activity for the whole system. The ethane-propane mixture to ethylene. This iso Abutane-ethylene mixture has the composition hydrocarbon eiiiuent from the secondary settler, in an amount shown in the table, is washed with aqueous sodium hydroxide and passed to sepa rating means 6E) for separation and recovery of portions and the isobutane-ethylene stream is 25 various fractions. This net hydrocarbon effluent split into six equal portions. To the bottom of has the composition shown in the table. Except each of reactors I2 and,I4 is passed one of the for a small amount of entrained catalyst, the hy isobutane portions, one of the isobutane-ethylene drocarbon recycle passing through pipes 5I and shown in the table and is charged in the amount shown. The isobutane is split into two equal portions, one-half of the recycle passing through 30 has the same composition. . pipe 3U, and about 6,150 volumes per day of a 30 It is to be appreciated that various modifica liquid hydrocarbon-aluminum chloride complex tions of my invention can be practiced without catalyst from pipe 2I. To the middle of each of departing from the teachings and spirit of the the primary reactors I2 and I4 is charged an disclosure, or from the scope of the claims. The other one of the six portions of the isobutane ethylene portions. As the hydrocarbon-catalyst mixture passes upwardly through these reactors Isobutane IsobutaneNet feed pipe ethylene ei‘liuent l0 feed pipe ll pipe 55 Volume/day _________ ._ Comp., mol percent: Methane 6, 363 3, 318 Recycle pipe 51 9, 156 140, 000 ' and lighter _________ _ _ 10. 4 4. 5 Ethylene. _ _ 35. 3 1. 2 Ethane___.Propylene. . " 13.2 3. l 5. 7 0.0 Propane.... Isobutane ........ _ . N. butane _ . 2. 9 5. 3 32.4 61.5 2.7 8.0 Diisopropyl ............................ . . 8. 6 Other 05+ ............................. _ . 5. 2 100. 0 100.0 100.0 it is intimately admixed by the efficient stirrer 2t. lThe proportions of the materials charged insure that the liquid hydrocarbon mixture is'in the continuous phase, with finely divided particles of the liquid catalyst complex, having a maximum particle diameter between about l0 and 20 mi crons, dispersed throughout. The reaction tem peratureranges up to about 125°.F.»a's a maxi claims are not to be unduly limited by limita tions shown in the specific examples. I claim: 1. An improved process for reacting ethylene and isobutane to form diisopropyl, which .com prises conducting said reaction in two sets of re actors having two reactors in each set, passing a portion of an isobutane feed to the bottom of the first reactor of each set, passing a portion of an isobutane-ethylene feed to the bottom of each of said reactors and also to an intermediate point -` of the first reactor of each set, passing from a common catalyst source a portion of a liquid aluminum chloride-hydrocarbon complex catalyst to the bottom of the first reactor of each set in an amount not greater than that which will permit said catalyst to be the dispersed phase in the resulting admixture, maintaining an alkylation temperature in each said reactor, passing an in timate hydrocarbon-catalyst admixture from the top of the first reactor of each set to the bottom sit CPI of the second reactor of the respective set, flow, ing the contents of each reactor from bottom to top and effecting a vigorous stirring of the con tents of each said reactor to establish an inti mate admixing of the contents thereof, passing the eiiluents of each second reactor to a corre mum, and the volume of cooled recycle is such sponding primary settling zone to separate a liquid 4vthat the overall temperature rise is not more than about 15 to 20° F. Under these conditions hydrocarbon material containing a minor amount liquid phase operation isassured with a pres of entrained catalyst from the bulk of the ad sure not, greater than about 40G-420 pounds per mixed catalyst, combiningthe hydrocarbon elilu square inch gage. From the top of each ofthe 65 ents of each primary settling zone and combining primary reactors, the reacting admixture passes the catalyst effluents of each primary settling to the bottom of the Acorresponding secondary zone, passing at least a portion of said combined reactors, I3 and I5, with one of the remaining hydrocarbon eii‘luents to a secondary settling zone two portions of the isobutane-ethylene charge wherein substantially all of the remaining en being added just as it enters the secondary re' 70 trained catalyst is separated fromthe effluents, actor. Each of the primary and secondaryre removing from said secondary settling zone a actors has a capacity of about '72 volumes. The hydrocarbon material- and recovering therefrom upñowing material is also intimately admixed a diisopropyl fraction as a product of the proc in the secondary reactors, and Vpasses from the ess, removing also from said secondary settling top of each secondary reactor to a corresponding 75 zone liquid catalyst, and combining said liquid 2,409,389 9 10 catalyst with the aforesaid combined catalyst eliiuents to form a uniform catalytic material as uid hydrocarbon material containing a minor amount of entrained catalyst from the bulk cf the aforesaid common catalyst source. the admixed liquid catalyst, combining the hy ' 2. In a process for reacting an alkylating re actant and an alkylatable hydrocarbon in tbe presence of a liquid alkylation catalyst under al kylation reaction conditions, the improvement drocarbon eiiiuents of each primary settling Izone and combining the catalyst efliuents of each pri mary settling zone, cooling a portion of said com bined hydrocarbon eiliuents and passing saine to the bottom of the iirst reactor of each said set, passing a further portion of said combined hy which comprises conducting said reaction in at least two series of reactors having two reactors in_each set, passing an alkylatable hydrocarbon 10 drocarbon eiiluents to a secondary settling zone and removing therein substantially all of said en feed to the bottom of the first reactor of each trained catalyst from the hydrocarbon efliuents, set, passing a mixture of alkylatable hydrocarbon recovering an alkylate product from the resulting and alkylating reactant to the bottom of each hydrocarbon eíiiuents, admixing said separated of said reactors and also to an intermediate point of the ñrst reactor of each set, passing from a 15 catalyst with the aforesaid combined catalyst common catalyst source a portion of a liquid al effluents to produce a common catalyst source as lrylationrcatalyst to the bottom of the iirst re actor of each set in an amount not greater than that which will permit said catalyst to be the dis aforesaid, and adjusting the catalyst contained in said common catalyst source to maintain a desired catalytic activity by withdrawal of a por persed phase in the resulting admixture, passing 20 tion thereof as spent catalyst and by addition of an intimate hydrocarbon-catalyst admixture from the top of the iirst reactor of each set to the bottom of the second reactor of the same set, ñowing the contents of each reactor from bottom to top and effecting a vigorous and'intimate mix 25 ing of the contents of each said reactor, passing fresh catalytic constituents. 3. The process of claim 2 in Which said alkyl atable hydrocarbon is a low-boiling isoparaiiin, said alkylating reactant- is a low-boiling oleñn, and said liquid catalyst is a liquid hydrocarbon aluminum chloride complex. the eiiluents of each second reactor to a corre sponding primary settling zone to separate a liq CLARENCE R. RINGHAM.