the catalyst of the present invention comprises a titanium subfluoride on a suitable support containing surface hydroxyl groups , preferably a group iii - a metal oxide . the support must contain hydroxyl groups which will react with the titanium component . once the titanium tetrachloride is supported on the support , it is reduced with hydrogen to form the subhalide . the group iii - a metal oxides possess the necessary surface hydroxyl groups . specific examples of the group iii - a metal oxides which possess surface hydroxyl groups and which also possess a relatively high surface area include alumina , gallium oxide , indium oxide , and thallium oxide . of these compounds , the preferred support is alumina , and especially low density , high surface area aluminas such as gamma - alumina or , if so desired , eta - alumina . the apparent bulk density of the alumina is preferably 0 . 3 to 0 . 8 g / cm 3 , with a surface area of 1 to 500 m 2 / g . the alumina may be in any shape , e . g ., spheroidal alumina , as prepared by the well known oil - drop method . the alumina may be treated to provide greater physical stability , e . g ., impregnated with a compound such as barium nitrate , which upon calcination is converted into barium oxide . a commercial gamma - alumina may also be used as the support . since this commercial gamma - alumina could contain an excessive amount of water which would consume an excess of titanium tetrahalide without any beneficial effect on the catalyst , in the preferred embodiment of this invention , the commercial gamma - alumina is subjected to a predrying step by heating to 300 ° to 600 ° c in inert gas or hydrogen flow for 1 to 10 hours . this predrying step is used when preparing a catalyst using the sublimation method or when using an impregnation method using a titanium tetrafluoride solution in organic solvents . however , if the catalyst is prepared by using an aqueous titanium hexafluoric acid as the impregnating agent , the commercial gamma - alumina can be used without predrying . if the catalyst is further supported on an inert carrier , any well known inert supports can be used . these include silica , clays , charcoal , gravel , sand , etc ., though all of these will not give equivalent results . it is also within the scope of the present invention to add one or more promoters to the catalyst system . it is believed that use of one or more promoters , e . g ., group viii and group vi - b metals , may be beneficial to the practice of the present invention . when it is desired to use the catalyst system in an alkylaromatic isomerization process , then alkylaromatic isomerization reaction conditions should be used . reaction conditions are disclosed in u . s . pat . no . 3 , 637 , 881 ( class 260 - 688a ), the teachings of which are incorporated by reference . when it is desired to use the catalyst system of the present invention for alkylaromatic transalkylation , then appropriate reaction conditions should also be used . these are disclosed in u . s . pat . no . 3 , 720 , 726 ( class 260 - 672t ), the teachings of which are incorporated by reference . reaction conditions for the alkylation of aromatic hydrocarbons will be discussed in detail in a latter part of this specification . two different catalyst preparation techniques may be used , sublimation an impregnation . in one sublimation procedure titanium tetrafluoride may be placed on top of a bed of gamma - alumina . preferably the alumina is predried at 300 ° to 600 ° c for 1 to 10 hours under hydrogen or nitrogen flow to activate the alumina and desorb all water therefrom . drying should not be so severe to remove the surface hydroxyl groups necessary for an active catalyst . non - predried , commercial alumina may also be used but there will be a significant loss of tif 4 to titanium oxide or titanium oxyfluoride . the titanium tetrafluoride and alumina should be maintained in a dry , inert atmosphere , after drying . while passing nitrogen downflow over the mixture of alumina and titanium tetrafluoride , the temperature is slowly increased to a temperature slightly above the sublimation temperature of titanium tetrafluoride , 284 ° c , then the temperature is increased , to higher temperatures . temperature as high as 700 ° c may be used in this step . heat treatment at higher temperatures may be omitted . following this , the titanium is reduced to a lower oxidation state than + 4 by treatment with flowing hydrogen at 400 ° to 700 ° c . another sublimation technique is to mix the titanium tetrafluoride with a desired amount of substrate and heat the mixture to a temperature in excess of 300 ° c in an inert gas such as nitrogen , or if so desired , in hydrogen gas . following this , the reduction of the titanium to a valence state of less than + 4 is effected in a manner similar to that hereinbefore set forth . upon completion of the final treatment , the finished catalyst should be sealed under a dry , inert atmosphere . another way to prepare catalyst for use in the present invention is to impregnate the support with a solution containing a compound which will decompose to form titanium tetrafluoride . a preferred titanium tetrafluoride impregnating solution consists of an organic polar solvent solution or aqueous solution of tif 4 in water , or an aqueous solution of m 2 mif 6 , where m equals h , li , na , or k . in all impregnating methods is is preferred to contact the support with impregnating solution at room temperature and then progressively increase the temperature to evaporate the solvent . the catalyst is then preferably heated to 200 ° to 600 ° c under an inert atmosphere and then reduced with hydrogen at 400 ° to 700 ° c . the catalyst should be stored in a dry , inert atmosphere . unfortunately , the sublimation procedure required excess amounts of titanium compounds to insure that all parts of the support are contacted by titanium compounds . because of the difficulties encountered with this procedure , the impregnation route is much preferred . in impregnation , it is of course possible to vary over a wide range the concentration of titanium compound in the finished catalyst system . at least about 0 . 5 weight percent titanium is believed necessary for a significant amount of catalytic effect to occur . the upper limit on titanium is believed to be about 20 %. the ratios of reactants and other reaction conditions which occur when alkylating benzene with light olefins are basically those well known in the art . it is desirable to maintain pressures high enough to have a liquid phase in the reaction zone . preferred pressure seems to be around 20 to 60 atm , with an optimum pressure of about 35 atm . temperature effects the conversion of olefins . temperature may range between ambient and 250 ° c . at very low temperatures , the catalyst is not sufficiently active to permit the desired reaction to proceed at a satisfactory rate . at very high temperatures , it is believed that the catalyst may be damaged by formation of carbonaceous materials on the catalyst . preferred operating temperatures seem to be about 100 ° to 200 ° c . it is difficult to pick an optimum temperature , but this may be because conversion of olefins is so high . further studies , with less conversion , may indicate an optimum temperature for this reaction . the catalyst may be disposed in a reactor vessel as a fixed , fluidized or moving bed of catalyst . the reactants may contact the catalyst in upflow , downflow or cross - flow fashion , though upflow of reactants over a fixed bed of catalyst is preferred . the liquid hourly space velocity in the reactor may range from 0 . 1 to 20 . because catalyst of the present invention is very active for the alkylation reaction , significantly higher space velocities are possible than when using some prior art catalysts , e . g ., spa . to some extent , the liquid hourly space velocity is related to temperature in the reaction zone , in general , a higher lhsv will require higher temperature operation . the catalyst of the present invention has a number of advantages over spa . spa is a very poor catalyst for alkylation of benzene with ethylene , but is satisfactory for alkylation with propylene . the alkylation of benzene with propylene over spa is only economically feasible at high benzene to propylene ratios . with high ratios ( about 8 to 1 molar ), cumene is produced in high yields , with very little production of polyalkylated species . production of di - and tri - alkylated species must be minimized because spa does not catalyze transalkylation , so the polyalkylated species must be discarded . the process of the present invention permits alkylation of an aromatic with ethylene , propylene , or heavier olefins . any polyalkylated species formed can be recycled and transalkylated to the desired product , in the same or a separate reactor containing the catalyst of the present invention . the catalyst used in the process of the present invention is slightly less active than either bf 3 or alcl 3 for transalkylation or alkylation of benzene with ethylene . however , the process of the present invention does not have the corrosion problems associated with bf 3 and alcl 3 . further , at slightly higher temperatures , the titanium subfluoride catalyst used in the process of the present invention can do the same job as bf 3 or alcl 3 , without the headaches of bf 3 addition or sludge reactors . for alkylation of aromatics with higher molecular weight olefins , e . g ., propylene , and heavier olefins , bf 3 and alcl 3 are too active and produce polyalkylated species . bf 3 and alcl 3 are also too acidic to be good transalkylation catalysts , causing at times more dealkylation than alkyl transfer . accordingly , one of the outstanding advantages of the process of the present invention is that it is capable of both alkylating and transalkylating propyl groups , and even higher molecular weight alkyl groups . this is a distinct commercial advantage in that it permits a refiner to operate his alkylation reactor at , e . g ., lower benzene to propylene ratios . benzene to propylene ratios of around 3 are believed to be optimum when the process of the present invention is applied to the benzene recycle will be required . in addition , the polyalkylated species produced can be transalkylated with benzene to produce more cumene , with practically complete elimination of any disposal of polyalkylated species . the catalyst used in the process of the present invention is also believed to have excellent characteristics for a detergent alkylation process . it should be possible to alkylate benzene with olefins having a carbon chain length of 5 to 20 , and preferably 8 to 16 . in the past , hf acid has been used to catalyze the alkylation reaction wherein benzene contacts the olefin in the presence of liquid hf acid , which is very corrosive . alcl 3 and bf 3 are not believed suitable for the production of detergent alkylate , because as hereinbefore mentioned , they are too active and produce polyalkylated species . an aqueous solution of titanium hexafluoric acid was used to impregnate gamma - alumina . the alumina was 1 . 6 mm spheres , with an abd of 0 . 52 . 300 cc ( 156 . 6 g ) of alumina was impregnated with 250 ml of the aqueous solution which contained 10 cc of 60 % h 2 tif 6 . after impregnation , the impregnation product was placed in a pyrex glass reaction vessel and treated as follows : ______________________________________ stage one stage two stage three______________________________________t , ° c 140 300 550hours 1 2 . 5 3 . 0gas n . sub . 2 n . sub . 2 h . sub . 2flow , cc / min 1500 1500 1500______________________________________ this was catalyst a . it contained 1 . 32 wt . % ti and 4 . 2 wt . % f . this catalyst , 50 cc ( 25 . 3 g ) was loaded into a 0 . 78 inch i . d . stainless steel . benzene and ethylene , in a mole ratio of 8 : 1 , were passed upflow through the reactor at 170 c , 200 psig ., and 4 . 0 lhsv . the liquid product contained : 325 cc ( 169 g ) of 1 . 6 mm diameter gamma - alumina spheres which possessed an abd of 0 . 52 was impregnated in a steam rotary drier with a solution of 10 ml ( 16 . 99 g ) of 60 % h 2 tif 6 diluted to 350 ml with de - ionized water . the impregnation product was subjected to the following treatments : ______________________________________ stage one stage two stage three______________________________________t , ° c 140 300 550hours 1 1 . 5 3gas n . sub . 2 n . sub . 2 h . sub . 2flow , cc / min 800 800 1000______________________________________ the finished catalyst contained 1 . 74 wt . % ti and 3 . 7 wt . % f . a 50 cc sample weighed 26 . 38 g . this sample of catalyst was loaded into a vertical tubular ( i . d . = 1 . 25 inch ) glass reactor in a heating means . ethylbenzene vapor was passed downflow over the catalyst . ethylbenzene flows were 26 . 1 g / 100 min at 200 c , and 23 . 6 g / 100 min at 250 c under atmospheric pressure . helium ws continuously added at the rate of 10 cc / min , as measured . the liquid product was collected in an ice bath . the liquid product contained : ______________________________________ weight percent atcomponent 200 c 250 c______________________________________non - aromatics 0 . 1 0 . 1benzene 2 . 2 3 . 6toluene 0 . 5 0 . 3ethylbenzene 94 . 1 90 . 11 , 3 deb 1 . 8 3 . 71 , 4 deb 1 . 2 1 . 81 , 2 deb 0 . 1 0 . 4______________________________________ for comparison purposes , the transalkylation activity of bf 3 catalyst was tested . this catalyst , bf 3 supported on alumina , was loaded into the same reactor used in reactor 2 . ethylbenzene vapor was passed under atmospheric pressure downflow over the catalyst at 14 . 9 g / 100 min at 200 ° c with he flow of 10 cc / min . the liquid product contained : ______________________________________component wt . % ______________________________________non - aromatics -- benzene 1 . 1toluene 0 . 1ethylbenzene 96 . 81 , 3 deb 1 . 11 , 4 deb 0 . 81 , 2 deb 0 . 1______________________________________ thus , even at lower flow rates the bf 3 did not possess the transalkylation activity of catalyst of the present invention . catalyst of the present invention was prepared by impregnating 325 cc of 1 . 6 mm diameter gamma - alumina spheres with a solution prepared by diluting 30 ml ( 49 . 01 g ) of 60 % h 2 tif 6 to 350 ml with de - ionized water . the alumina and impregnating solution were placed in a steam rotary drier . the materials were contacted for 20 minutes with rotation of the drier , but without steam . steam was then admitted to the steam jacket of the drier and the solution evaporated to dryness with rotation of the drier . the impregnated material was then subjected to the following treatment : ______________________________________ stage one stage two stage three______________________________________t ° c 140 300 550hours 1 . 0 1 . 67 3 . 0gas n . sub . 2 n . sub . 2 h . sub . 2flow , cc / min 800 800 800______________________________________ the finished catalyst contained 5 . 37 wt . % ti and 6 . 8 wt % f . this catalyst was tested for its ability to catalytically convert cumene . the feed to the unit was a dried , technical grade cumene , with the following analysis : this material was passed upflow over 50 cc ( 28 . 78 g ) of the catalyst at varying reaction conditions . the results are reported in the following table . the pressure was held constant at 35 atm , absolute . __________________________________________________________________________ hours non - isopro - di - iso - on temp plant aro - un - pyl - ben - un - propyl - un - ethyl - period stream ° c lhsv psig matic benzene known zene known benzene known benzene__________________________________________________________________________1 5 - 9 140 4 500 0 . 1 12 . 0 0 . 1 63 . 5 0 . 4 22 . 6 1 . 0 0 . 32 9 - 13 140 4 500 0 . 1 12 . 5 -- 62 . 5 0 . 3 23 . 3 1 . 0 0 . 34 13 - 17 140 4 500 0 . 1 12 . 5 -- 62 . 8 0 . 3 23 . 0 1 . 0 0 . 37 33 - 37 140 2 500 0 . 2 14 . 9 0 . 1 55 . 2 0 . 4 27 . 3 1 . 6 0 . 311 53 - 57 120 2 500 0 . 1 8 . 3 -- 73 . 6 0 . 7 16 . 5 0 . 5 0 . 315 73 - 77 120 4 500 -- 6 . 3 -- 80 . 7 0 . 1 12 . 6 tr 0 . 319 89 - 93 -- -- -- -- 5 . 9 -- 82 . 6 0 . 1 11 . 1 tr 0 . 320 97 - 101 140 4 500 0 . 1 12 . 1 -- 63 . 9 0 . 1 23 . 5 0 . 1 0 . 224 113 - 117 -- -- -- 0 . 1 11 . 2 -- 66 . 2 0 . 1 22 . 1 0 . 1 0 . 225 121 - 125 140 1 500 0 . 2 15 . 4 -- 53 . 4 0 . 6 30 . 0 0 . 1 0 . 327 133 - 137 -- -- -- 0 . 2 16 . 0 -- 52 . 8 0 . 2 30 . 3 0 . 3 0 . 2all analyses are given in weight percent__________________________________________________________________________