US2847488A - Isomerization and alkylation of hydrocarbons - Google Patents

Description

Aug. l2, 1958 H. G. BQYNTON Em 2,847,488

ISOMERIZATION AND ALKYLATION OF HYDROCARBONS Filed Sept. '7, k1954 United States Patent Oice 2,847,488 Patented Aug. 12, 1958 ISOMERIZATION AND ALKYLATION OF HYDROCARBGNS Harry G. Boynton and Joseph T. Horeczy, Baytown, Tex., assignors, by mesne assignments, to Esso Research and Engineering Company, Elizabeth, N. J., a corporation of Delaware Application September 7, 1954, Serial No. 454,384

12 Claims. (Cl. 260-68353) The present invention is directed to a method of removing alkyl chlorides frorn hydrocarbons containing them. More particularly, the invention is concerned with removing alkyl chlorides from hydrocarbons undergoing isomerization and alkylation. In its more speciiic aspects, the invention is concerned with removing alkyl halides from parafiins and isoparafiins charged to a combined isomerization and alkylation operation;

This application is a continuation-inpart of Serial No. 281,042, lled April 7, 1952, and now abandoned, entitled Hydrolysis of Ethyl Chloride in Hydrocarbons, which is a divisional application of Serial No. 227,267, filed May 19, 1951, now Patent No. 2,761,888, in the names of Joseph T. Horeczy and Harry G. Boynton, entitled Hydrolysis of Alkyl Chlorides in Hydrocarbons.

In the catalytic conversion of hydrocarbons in which aluminum chloride is used as a catalyst, such as in the alkylation of an isoparain with an olefin or in the isomerization of a normal paraffin to an isoparaiin, the product frequently contains alkyl chlorides which act as contaminants. The products, when isoparains are alkylated with olefins, usually boil in the gasoline boiling range and the alkyl chloride contaminating the product also boils in the gasoline boiling range and as a result it is diflcult to remove the contaminating alkyl chloride from the desired product.

In the aforementioned alkylation, it is customary to alkylate isobutane with ethylene and the like. The products contain alkyl chlorides and also the unreacted iso and normal butanes which are an effluent from the operation are contaminated with ethyl chloride. This ethyl chloride is formed during the alkylation of isobutane with ethylene in the presence of aluminum chloride catalyst and HCl promoter by a reaction which may involve ethylene and HC1. HCl appears to be quantitatively converted to ethyl chloride with a portion of the ethyl chloride, perhaps to 20%, being consumed in promoting the alkylation reaction. The major portion of the ethyl chloride, however, passes out from the alkylation reaction zone in solution in the unreacted isobutane and the normal butane which usually is present with the isobutane. Ethyl chloride forms an azeotrope with isobutane which has been estimated by the method of Carlson and Colburn, Industrial Engineering Chemistry, vol. 34, page 585 (1943) utilizing the Van Laar equations to lie very close to the boiling point of pure butane. Thus with the boiling point of isobutane-ethyl chloride azeotrope and isobutane being substantially identical, the ethyl chloride may not be readily separated therefrom by fractional distillation.

Normal butane and ethyl chloride also form an azeotrope which makes a separation between the two compounds by distillation ditlicult. Hence, other means are necessary to remove ethyl chloride.

The presence of alkyl chlorides in hydrocarbons, when the hydrocarbons are to be used as a motor fuel, is quite detrimental in that certain of the alkyl chlorides act as detonating agents or may react with anti-knock agents which are added to the gasoline. It is, therefore, quite desirable that alkyl chlorides present in`hydrocarbons for any reason and frequently as a result of a catalytic conversion operation should be removed therefrom before the hydrocarbon is generally suitable as a gasoline component and particularly an aviation gasoline component.

The presence of ethyl chloride in isobutane, fractionated from an alkylation reactor euent, which would be recycled to the aluminum chloride saturater in the alkylation operation as a means of introducing fresh aluminum chloride to the reaction zone is quite detrimental. lf the ethyl chloride is not separated from the isobutane recycle stream, the solubility of aluminum chloride in isobutane is adversely affected and severe sludging in the aluminum chloride saturater takes place. Concentrations above about 0.4 mole percent ethyl chloride in the butane passed through the aluminum chloride saturater may not be tolerated due to excess sludging. In concentrations of 0.1 mole percent, some sludging in the aluminum chloride saturater may occur. Without facilities for removal of ethyl chloride, ethyl chloride concentrations in excess of 0.4 mole percent may be built up in the isobutane recycle stream in a very short time. If efforts are made to separate the ethyl chloride by fractionation, the ethyl chloride may not be removed and in fact will be concentrated in the isobutane fraction.

Furthermore, if the total butane stream from an alkylation reactor is employed as a feed to an isomerization reaction zone in which aluminum chloride is employed and in which the aluminum chloride is carried into the reaction Zone by pickup with the feed, the same problem of sludging will exist in the aluminum chloride saturater and in the isomerization reaction zone. The fact of the matter is in both the alkylation and isomerization reactions employing aluminum chloride where ethyl chloride is present, the reaction rapidly becomes inoperable due to sludging.

Accordingly, the present invention may be briefly de scribed as involving treating a light hydrocarbon such as normal butane and isobutane containing ethyl chloride by contacting the light hydrocarbon in the liquid phase with an aqueous solution of an alkali metal hydroxide at an elevated temperature for a suiiicient length of time to convert the ethyl chloride to an alcohol following which the alcohol may be removed from the hydrocarbon and the treated hydrocarbon is recovered substantially free of ethyl halide. Y

The present invention is specifically directed to a combination process of isomerization and alkylation of hydrocarbon in which a hydrocarbon is isomerized in the presence of a Friedel-Crafts catalyst and the isomerized hydrocarbons then employed as a feed stock for alkylation of olens in the presence of a Friedel-Crafts catalyst, the particular feature being removing alkyl halides from the hydrocarbons being charged to the isomerization and the alkylation steps, the removal of the alkyl halides being accomplished by hydrolysis of the alkyl halides at elevated temperatures in the presence of an aqueous solution of an alkali metal hydroxide, such as sodium hydroxide.

The catalysts employed in the isomerization and/or alkylation steps are the Friedel-Crafts type catalysts such as the aluminum halides, as exemplied by aluminum chloride, aluminum bromide, aluminum iodide, aluminum fluoride, boron triiluoride, iron chloride, complexes thereof with organic and inorganic compounds, and other halogen-containing catalysts, such as hydrogen fluoride, and the like. Preferably, the catalyst is aluminum chloride.

Ordinarily the liquefied light hydrocarbon fraction which forms a feed stock of the present invention will 3 contain an amount no greater than by volume of an alkyl chloride. Usually the liquefied light hydrocarbon feed is a mixture of isobutane and normal butane and the feed may contain in the range from about 0.01 to 0.5 mole percent of ethyl chloride when aluminum chloride is employed as an alkylating agent and the light hydrocarbon, such as butanes is an efuent stream therefrom. However, the hydrocarbon feed stock may result from any processing operation in which it becomes contaminated with an alkyl chloride. As mentioned before, such operation may include the alkylation of an isoparan with an olefin when employing aluminum chloride as a catalyst or the isomerization of a normal paran to an isoparan employing aluminum chloride as a catalyst. When the hydrocarbon containing alkyl chloride is formed in the aforementioned alkylation operation and is in the gasoline boiling range, it may contain from about 1% to about 2% by volume of ethyl and/ or isopropyl chloride. Likewise the hydrocarbon mixture may result from the chlorination of a hydrocarbon wherein a mixture of a hydrocarbon and alkyl chloride is obtained in which the mixture contains an amount no greater than 5% by volume of an alkyl chloride.

The hydrocarbon feed stock, as mentioned before, may boil in the gasoline boiling range from about 65 up to about 450 F. The hydrocarbon feed stock may have such a boiling range especially if it is formed by the alkylation of an isoparan with an olefin with the isoparaflin having 4 carbon atoms in the molecule and the olefins having from 2 to 4 carbon atoms in the molecule. Generally the gasoline boiling hydrocarbons in an alkylate fraction of this nature may contain from about 5 to 16 carbon atoms in the molecule.

The light hydrocarbon employed in the present invention is preferably isobutane but may be a mixture of isobutane and normal butane. The feed stock to the present invention may suitably be obtained as an effluent from an alkylation reaction in which ethylene and isobutane are reacted to form an alkylate employing aluminum chloride as the catalyst.

The alkyl chlorides present in the hydrocarbon feed of the present invention will usually comprise ethyl and isopropyl chlorides. The alkyl chlorides serving as a contaminant in the feed stock of the present invention may be exemplified by the following compounds: tertiary butyl chloride, 2,3-dimethyl-2-chloro butane and secondary butyl chloride.

In practicing the present invention it is desirable to contact the contaminated hydrocarbon feed stock containing alkyl chlorides with an aqueous solution of an alkali metal hydroxide at an elevated temperature.

The elevated temperatures will range ordinarily from 180 to 500 F. with a preferred temperature in the range from about 290 to 500 F.

At the lower temperatures in the range given it is necessary that a longer time of contact be employed than at the higher temperatures. For example, at the lower temperatures it will be necessary to use longer contact times of the order of 50 to 60 minutes, whereas at the higher temperatures shorter contact times may be employed; for example, the time should usually be in excess of .about 3 minutes depending on the temperature level at which the treating operation occurs. At about 325 F., in removing isopropyl chloride from an alkylate of the nature given, a contact time of about minutes will give substantially complete removal of isopropyl chloride.

It is desirable to maintain the hydrocarbon which is being treated in the liquid phase; therefore, pressures may be superimposed during the reaction to maintain a liquid phase treatment.

The alkali metal hydroxide may be an aqueous solution of an alkali metal hydroxide, such as sodium, potassium or lithium hydroxide. It will be preferred, however, to use an aqueous solution of sodium hydroxide 4 containing an amount of sodium hydroxide in the range between 1% and 30% by weight of the solution. A preferred range of sodium hydroxide concentration in the aqueous solution is an amount in the range between 2% and 15% by weight.

The present invention will be illustrated by reference to the drawing in which the single figure is a flow diagram of a preferred mode.

Referring to the drawing, numeral 11 designates a charge line controlled by valve 12 by way of which isoand/or normal butane are introduced into the system from a source not shown. This isoand/or normal butane fraction may be fractioned from virgin crude petroleum or may be produced in a catalytic cracking operation and the like; preferably it is a fraction of crude petroleum.

ln any event, the isoand/or normal butane are introduced by line 11 into a fractionation zone 13 which may be a single distillation tower or a series of distillation towers equipped with internal vapor-liquid contacting means for intimate contact between vapors and liquids to allow a ready separation between the isoand normal butane. It is to be understood that fractionation zone 13 is provided with all auxiliary equipment ordinarily associated with the modern distillation tower and will include means for inducing reflux, and the like.

The temperatures in distillation zone 13 may be adjusted by a heating means, such as a steam coil 14, to provide a suflcient temperature and pressure to make a separation between isoand normal butane. The isobutane is removed overhead from zone 13 by line 15v while the normal butane is also removed as a side stream by line 16. Heavier fractions, such as pentanes and the like, may be discharged by line 17.

The normal butane in line 16 is charged into a heating means 18 provided with a coil 18a which raises the temperature of the normal butane to a temperature in the range from about to about 450 F. and causes vaporization of the normal butane. The normal butane then is discharged into line 19 and thence into line 20 controlled by valve 21 into an isomerization reaction zone 22 which may contain a bed of supported aluminum chloride catalyst 23 arranged on grid plate 24. The bed of aluminum chloride catalyst 23 may suitably be aluminum chloride on alumina, such as Porocel.

The liquid hydrocarbon charge rate to the isomerization reaction zone 23, which is maintained at a temperature in the range between 100 and 450 F. may be of the order of about 0.1 to 5.0 v./V./hr. which is sucient to cause substantial conversion and isomerization of the normal butane to isobutane, the reaction product being discharged from zone 22 by line 25 for further treatment as will be described.

From time to time, the aluminum chloride in the reaction zone 22 may become depleted and it is desired to introduce makeup aluminum chloride. This may be done by discharging a portion of the vaporized normal butane in line 19 into aluminum chloride saturator 26 which may contain a body 27 of aluminum chloride as lumps or the like. By opening valve 28 in line 19 the vaporized butane passes through the saturator 26 and picks up aluminum chloride which sublimes and carries same by line 29 into line 20 and thence into zone 22 for deposition of aluminum chloride on the support therein. The aluminum chloride may be introduced either intermittently or continuously into the zone 22 as has been described.

It may be desirable to adjust the temperature of the vaporized normal butane and this may suitably be done by bypassing a portion of the normal butane around heater 18 by bypass line 30 controlled by valve 31, valve 32 in line 16 being partially throttled or closed.

The isobutane in line 15 is charged into a heating or cooling means 33 provided with a coil 34 wherein the temperature of the isobutane is adjusted for alkylation.

'Ihis temperature may be in the range from about 40 to about 200 F. and depending on the temperature desired for alkylation, the heating or cooling means 33 may be suitably adjusted. In any event, the isobutane is discharged from heater or cooler 33 by line 35 into line 36 controlled by valve 37 and thence into an alkylation reaction zone 38 provided with a bed of 'supported aluminum chloride catalyst 39 suitably arranged on a grid plate 40. Like the bed 23 in zone 22, the bed 39 may be aluminum chloride on alumina, such as is known to the trade as Porocel. Y

The isobutane has added to it in line 36 an olefin, such as ethylene, propylene, butylenes, pentylenes, mixtures thereof, and the like, by Way of line 41 in an amount suiicient that the isobutane is in excess of the olefin.

An alkylation reaction takes place in zone 38 and the alkylate and unreacted reactants discharged therefrom by line42 to be further processed as will be described.

As the reaction takes place in zone 38, catalyst will be lost therefrom by sublimation and/or volatilization and, therefore, it is necessary to make up aluminum chloride which may be introduced by routing a portion of the isobutane in line 35 into aluminum chloride saturation zone 43 containing a body 44 of aluminum chloride such as lump aluminum chloride. Line 35 is controlled by Valve 45 which allows selected amounts of the isobutane to be bypassed through Zone 43 to pick up aluminum chloride by sublimation and volatilization and the bypassed iso butane then discharged back into line 36 by line 46.

The temperature control of the feed to the alkylation reaction zone 33 may be effected by bypassing a portion of the isobutane around the heating or cooling means 33 by way of bypass line 47 controlled by Valve 48. This is done by throttling or closing partially Valve 49 in line 15.

The product from isomerization reaction zone 22 is discharged by line 25, after cooling and condensing in condensation zone 25a, into an incorporator zone 50 after admixture with an aqueous sodium hydroxide solution introduced by line 51. The mixture of sodium hydroxide and isobutane and unreacted normal butane is then discharged by line 52 into a hydrolysis zone 53 provided with a heating means 53a which raises the temperature to a temperature in the range between 180 and 500 F. to cause hydrolysis of the alkyl halides to the corresponding alcohols. The product from the hydrolysis zone 23 is discharged by line 54 containing pump 54a which discharges the isoand normal butane after hydrolysis of alkyl halides into line 11.

Provision is made for recycling sodium hydroxide solution by line 55 to line 51. Used sodium hydroxide may be discharged by line 56 controlled by valve 57 while makeup is introduced into line 51 by opening valve 58.

The alkylation reaction product from zone 38 in line 42 controlled by Valve 59 is introduced into a fraction-ation zone 60 which may be similarly equipped to fractionation zone 13 to make a separation between the iso-A butane tand the light alkylate and also to allow withdrawal of heavy alkylate. Besides the usual equipment, zone 60, which may be a series or plurality of distillation towers, is provided with a heating means illustrated by steam coil 60a for adjustment of temperature and pressure to allow recovery as overhead isobutane which is withdrawn by line 6l and discharged thereby into line 25 for admixture with the isobutane from reaction zone 22. Heaver alkylate is discharged from the system by line 62 while light alkylate is withdrawn by line 63 and is admixed with sodium hydroxide solution and then -is introduced by line 64 controlled by valve 65 into incorporator or mixing device 66 `and thence by line 67 into hydrolysis reaction zone 68, which is similar to zone 53, and is provided with a heating means, such as steam coil 69. At the elevated temperatures indicated, which are the Same as in zone 53, the alkyl halides in the alkylate are hydrolyzed to the corresponding alcohols and the light alkylate free of alkyl halides is then withdrawn by line 70 for use as motor fuel while the aqueous sodium hydroxide solution is Withdrawn by line 71 for discard or recycle to line 64 for reuse in the operation.

It will be seen from the foregoing description of the drawing that a method is provided for removal of alkyl halides from the isoand normal butanes prior to charging same into the alkylation and Iisomerization operations, respectively.

If the alkyl halides were not removed from the isoand normal butane, these materials could not be used since sludging would occur in the aluminum chloride saturators 26 and 43 land in the reaction zones 22 and 38.

The present invention will be further illustrated by the following example:

EXAMPLE I In order to illustrate the invention further, runs were made in which a butane fraction containing ethyl chloride was subjected to hydrolysis in the liquid phase at elevated temperatures ranging from 150 to 305 F. The butane fraction containing ethyl chloride was introduced into a turbo-treater having a capacity of approximately 5 volumes, the treater being equipped with a stirring device turning at a constant rate of about 850 R. P. M. The power consumption for this treater, according to the method of Olney and Carlson, Chemical Engineering Progress, Vol. 43, page 473, was found to be about 0.93 H. P. an hour per barrel, assuming a contact time of 30 'minutes In these runs approximately 2 volumes of aqueous sodium hydroxide solution land approximately 2 volumes of butane containing about 0.13 mol percent of ethyl chloride were employed. The sodium hydroxide solution contained about l0 wt. percent of sodium hydroxide. Samples were removed from the contacting apparatus after 15, 30 and 60 minutes contact time and analyzed for chloride content. The results of these runs vare presented in Table I.

Table I l5 30 00 Minutes Minutes Minutes 1100% conversion was reached laf-fore the indicated time, because the ethyl chloride content was zero.

It will be noted from the data in Table I that at 150 F. only a small amount of ethyl chloride was removed after minutes contacting time. Whereas at 200 F. 42% of ethyl chloride was hydrolyzed. On the other hand, at the higher and preferred temperatures ranging from 250 to 305 F. from 87% to 100% removal of ethyl chloride 60 was realized.

EXAMPLE Il Normal pentane which contained approximately l volume percent of isopropyl chloride was divided into 8 portions each of which was contacted with an aqueous solution of sodium hydroxide at temperatures ranging from 250 to 330 F. in conducting runs on the 8 portions of feed stock a charge to each run consisted of about 2 volumes of either 2.4% or 11% aqueous sodium hydroxide solution and 2 volumes of hydrocarbon containing isopropyl chloride. The hydrocarbon and the isopropyl chloride differed in boiling points not more than 2 F. The charge was introduced into a turbo-treater having a capacity of approximately 5 volumes, the treater being equipped with a stirring device turning at a constant rate of about S50 R. l. lVi. The power consumption for this treater, according to the method of Olney and Carlson, Chemical Engineering Progress, vol. 43, page 473, was found to be about 0.93 H. P. an hour per barrel, assuming a contact time of minutes.

After the 8 portions had been `contacted as has been described With the sodium hydroxide solution, samples were removed after varying contact times and analyzed for chloride content expressed as weight percent chlorine. Pertinent data for the 8 runs are presented in Table II.

These high values indicate that each mole of ethyl chloride liberates a mole of hydrogen chloride which goes out in the solution in the butane.

EXAMPLE IV In order to illustrate further the eect of ethyl chloride on isobutane in the presence of aluminum chloride, isobutane containing ethyl chloride in the concentrations indicated in Example III was passed into an aluminum It will be seen from an inspection of the results given in Table II that at the higher temperatures the isopropyl chloride has been substantially removed after 30 minutes contact time, Whereas at the lower temperature, such chloride saturator at 170 F. and 4 liquid volumes of isobutane per volume of catalyst per hour. The results of these runs are presented in Table IV:

as 250 F., longer contact times were necessary to effect 30 Table IV substantial removal of the chloride.

Run No 8 9 10 EXAMPLE III Composition, Mol. To lllustrate the deleterious elect of ethyl Chlor1de Percent Feed Product Feed Product Feed Product on operation of an aluminum chloride saturator, such as 26 and 43, normal butane containing 2.7, 0.4 and 0.1 1.7 0.4 0.05 mole t f thl h1 .d d ,du h 2.1 1.4 1.4 3.6 3.0 .PSICCII 0. e y C OI'I e Was passe h Olnlg all 75.4 84 9 83.5 83.8 83.8 alummum chlorlde saturator at 170 F. at a l1qu1d feed 14-0 13-3 137 12-5 12-1 Isopentane. 4. 1 1. 0 0. 2 rate of 4 volumes of butane per volume of catalyst per CH. 9 9 hour. The results of these runs are presented in Table 40 Ethy1Ch10ride- 27 0-8 04 0-3 0 1 Trace III:

TABLE III Run No 1 2 3 4 5 6 7 Mol Percent Ethyl Chloride in Butane 2. 7 2. 7 0. 4 0. 4 0. 0. 0. 0 Wt. Percent A1inSo1ut1on 0. 050 0.071 0.103 0.093 0.083 0.087 0.087 Wt. Percent C1 1n solution..- 1.34 1.37 0. 98 1.02 0.43 0.39 0.34 Wt. Percent A1013 from .41--- 0. 2s 0.35 0. 51 0.46 0.41 0.43 0.43 Cl/Al M01 Ratio 13.0 14.7 7.2 8.4 3.9 3. 3.0 Cale. Values for Wt. Percent *Assuming all ethyl chloride which reacts goes to HCl.

It Will be noted from these data that the solubility It is to be noted that in the presence of ethyl chloride,

of aluminum chloride is appreciably reduced in the presence of 2.7 percent ethyl chloride but that smaller quantities have no discernible effect on the solubility. Moreover, when charging 2.7 and 0.4 mol percent ethyl chloride, the aluminum chloride was found on removal from the saturator to be severely sludgcd. With as little as 0.1 percent ethyl chloride in the butane feed, sludging of aluminum chloride began and aluminum chloride began sticking instead of dropping out of the saturator as a fluid as when ethyl chloride was not present in the butane. These data show that ethyl chloride concentrations above 0.4 mole percent in the butane passing through the saturator cannot be tolerated. At concentrations of 0.1 mole percent or less sludging does not occur to any appreciable extent.

The data further show that the chlorine in the butane leaving the saturator was appreciably higher when ethyl chloride was present in the butane. The chlorine to aluminum ratio in the catalyst which is normally 3.0, varied from 3.5 to 18.0 when ethyl chloride was present.

butane is converted to isopentane and heavier material, but very little if any isomerization to normal butane occurs. The data show that ethane is formed substantially mole for mole for each mole of ethyl `chloride which disappears.

In the alkylation step of the present invention the isoparaffin is preferably employed in excess of the olefin. A ratio of isoparain to olefin from about 5:1 to about 15:1 or higher may suitably be used.

The alkylation and isomerization steps may preferably be conducted in the presence of a promoter for the reactions. For example, hydrogen chloride or a substance yielding HCl may be used as a promoter. Water may be added to the reaction to generate HCl from the AlCl3 catalyst. The promoter may be used in an amount in the range between 10 mol percent and 150 mol percent based on the aluminum chloride or 0.1 to 4.0 mol percent based on olefin in alkylation reaction or 1.0 to 10.0 mol percent based on n-butane in isomerization reaction.

9 ln the contacting operation of the present invention in which butanes contaminated with ethyl chloride are contacted with aqueous alkali metal hydroxide solution at an elevated temperature, it is believed that the ethyl.

chloride is hydrolyzed to the corresponding alcohol. The alcohol on formation may go into solution in the aqueous solution of alkali metal hydroxide and may be recovered therefrom. In general, ethyl alcohol, formed from the corresponding ethyl chlorides, will dissolve in the aqueous caustic solution. Higher alcohols may remain in solution in the hydrocarbon. In the small quantities involved, such alcohols are beneficial to the performance rating of the fuel. The hydrocarbon is separated from the aqueous solution of alkali metal hydroxide and then may be water washed, if desired, to remove traces of caustic therefrom and may be used as a component of aviation fuel or as a feed stock to a conversion operation, as may be desiied, depending on its boiling points and properties.

It will be seen from the foregoing description and examples that the practice of the present invention involves treating an alkyl chloride contaminated hydrocarbon fraction at an elevated temperature with an aqueous solution of an alkali metal hydroxide for a sufficient period of time to cause conversion of alkyl halides such as ethyl chloride to the corresponding alcohol. The lower alcohols, such as ethyl, dissolve in the alkali metal hydroxide solution which is then separated from the hydrocarbon. As stated, the hydro-carbon may be washed with water to remove traces of caustic therefrom and subjected to other operations, such as fractional distillation and then may be used as `a blending agent in processing operations common to petroleum rening processes. A fraction such as one containing isoand normal butane after removal of ethyl chloride by hydrolysis, as described, may then be distilled. The process, it will be clear from the foregoing description, is a simple one readily adaptable and easy to use in the modern petroleum renery where many. operations involve the use of chloride-containing materials which serve to contaminate the desired hydrocarbon fractions.

While the present invention has been described and illustrated primarily in the removal of alkyl chlorides from alkylates and from gasoline boiling hydrocarbons, as Well as from the butanes such as isoand normal butane, it is to be understood that the invention is not to be restricted to fractions boiling in the gasoline boiling range. As mentioned before, isomerization products may become contaminated with alkyl chlorides, such as isobutane resulting from the isomerization of normal butane and the butanes elliuent from an alkylation reaction zone as described. Likewise, the invention is not restricted to paraf- Iinic hydrocarbons. It is frequently desirable to convert by isomerization one naphthenic hydrocarbon to another. For example, methylcyclopentane may be isomerized to cyclohexane, employing aluminum chloride as the catalyst. Since feed stocks to these processes may contain either naphthenic or paraffin hydrocarbons, the present invention is applicable to treatment of products therefrom for the removal of alkyl chlorides therefrom.

The nature and objects of the present invention having been completely described and illustrated what we wish to claim as new and useful and to secure by Letters Patent is: l

l. A process which comprises contacting normal butane with a supported Friedel-Crafts catalyst under isomerization conditions to form a reaction product containing normal butane, isobutane, and alkyl chlorides, removing said normal butane and said alkyl chlorides from said isomerization product and contacting said isobutane and an olefin with a supported Friedel-Crafts catalyst under alkylation conditions to alkylate said isobutane with said olefin.

2. A method as in claim 1 wherein said Friedel-Crafts catalyst is a supported aluminum chloride catalyst.

3. A method as in claim 2 wherein the said alkyl chlorides are removed from said isomerization product by hydrolysis at an elevated temperature in the presence of an aqueous solution of alkali metal hydroxide.

4. A method for preventing slndging in the isomerization and alkylation of hydrocarbons which comprises isomerizing normal butane to isobutane in the presence of supported aluminum chloride such that the isobutane contains an alkyl chloride, subjecting said isobutane containing alkyl chloride to hydrolysis in the presence of an aqueous solution of an alkali metal hydroxide at an elevated temperature to remove said alkyl chloride reco-vering from said hydrolysis isobutane substantially free of alkyl chloride, admixing an olefin with said isobutane substantially free of alkyl chloride, akylating said olen with said isobutane in the presence of a supported aluminum chloride catalyst to form a reaction product comprising unreacted isobutane and alkylate containing alkyl chlorides, and removing alkyl chlorides from said alkylate and isobutane by hydrolysis at an elevated temperature in the presence of an aqueous solution of alkali lmetal hydroxide.

5. In a method for catalytically converting a hydrocarbon by a Friedel-Crafts conversion process wherein said hydrocarbon is introduced into a conversion zone containing a bed of supported Friedel-Crafts catalyst, wherein a product stream is obtained containing alkyl chlorides formed during the Friedel-Crafts conversion process and wherein said product stream is subsequently brought into contact with a separate bed comprising a solid Friedel- Crafts catalyst, the improvement which comprises removing said alkyl chlorides from said product stream by hydrolysis at a temperature of about 290 to about 500 F. in the presence of an aqueous solution of an alkali metal hydroxide and then bringing said product stream into contact with said separate bed, whereby sludging of said separate bed is prevented.

6. A method as in claim 5 wherein the hydrocarbon is n-butane wherein said conversion zone is an isomerization zone for converting at least a portion of said n-butane to isobutane, wherein said product stream contains isobutane and alkyl chlorides, wherein said separate bed is a bed of supported Friedel-Crafts catalysts in an alkylation zone and wherein, after said hydrolysis of said alkyl chlorides said product stream is brought into contact with said Friedel-Crafts catalyst in said separate alkylation zone in the presence of an olefin to form an alkylate product.

7. A method for preventing sludging in the isomerization and alkylation of hydrocarbons which comprises the steps of isomerizing a normal paraiiin in an isomerization zone in contact with a supported aluminum chloride catalyst to form la product containing said paraffin, an isoparafin and alkyl chloride contaminants, removing said alkyl chloride contaminants from said isomerization product and recovering said isoparaiiin from said normal parain, admixing an olefin with said isoparan, alkylating said olefin with said isoparafiin in an alkylation zone in the presence of a supported aluminum chloride catalyst to form an alkylation reaction product comprising unreacted isoparaiiin, alkylate, and alkyl chloride contaminants, removing said alkyl chloride contaminants from said alkylation reaction product, recovering alkylate and isoparain from said alkylation reaction product, recycling said olen recovered from said alkylation product to said alkylation zone and recycling said normal paraffin recovered from said isomerization zone to said isomerization zone.

8. A method for preventing sludging in the isomerization and alkylation of a butane which comprises contacting normal butane with a supported aluminum chloride catalyst in an isomerization Zone under isomerization conditions to form an isomerization product containing unreacted normal butane, isobutane and alkyl chloride contaminants, subjecting said isomerization product to hydrolysis in the presence of an aqueous solution of an alkali metal hydroxide at an elevated temperature to remove said alkyl chloride contaminants, recovering isobutane and normal butane substantially free from alkyl chlorides, admixing an olefin with said recovered isobutane, contacting said isobutane-olefin mixture with a supported aluminum chloride catalyst in an alkylation zone under alkylation reaction conditions to form a reaction product containing unreacted isobutane, alkylate and alkyl chloride contaminants, removing said alkyl chloride contaminants from said alkylation product by hydrolysis at an elevated temperature in the presence of an aqueous solution of alkali metal hydroxide and recycling said normal butane recovered from said isomerization reaction product to said isomerization zone.

9. A method as in claim 8 wherein said isobutane recovered from said alkylation reaction product is recycled to said alkylation zone.

10. A method for preventing sludging in the isomerization and alkylation of a butane which comprises contacting normal butane with a supported aluminum chloride catalyst in an isomerization zone under isomerization conditions to form an isomerization product containing unreacted normal butane, isobutane and alkyl chloride contaminants, subjecting said isomerization product to hydrolysis in the presence of an aqueous solution of an alkali metal hydroxide at an elevated temperature in the range between 180 F. and 500 F. to remove said alkaline chloride contaminants, recovering isobutane and normal butane substantially free from alkyl chlorides, admixing an olefin with said recovered isobutane, contacting said isobutane-olefin mixture with a supported aluminum chloride catalyst in an alkylation zone under alkylation reaction conditions to form la reaction product containing unreacted isobutane, alkylate, and alkyl chloride contaminants, removing said alkyl chloride contaminants from said alkylation product by hydrolysis at an elevated temperature in the range between and 500 F. in the presence of an aqueous solution of alkali metal hydroxide and recycling said normal butane recovered from said isomerization reaction product to said isomerization zone.

11. A method in accordance with claim 10 in which the alkali metal hydroxide is sodium hydroxide.

12. A method as in claim 10 wherein the isoparafn is isobutane.

References Cited in the tile of this patent UNITED STATES PATENTS 1,253,055 Lacy Jan. 8, 1918 1,566,818 Carter et al Dec. 22, 1925 2,258,236 Benedict et al. Oct. 7, 1941 2,320,293 Ostergaard May 25, 1943 2,415,733 DOuville Feb. 11, 1947 2,435,621 Brooks et al. Feb. 10, 1948 2,535,735 Groebe et al. Dec. 26, 1950 2,761,888 Horeczy et al. Sept. 4, 1956

Claims (1)

1. A PROCESS WHICH COMPRISES CONTRACTING NORMAL BUTANE WITH A SUPPORTED FRIEDEL-CRAFTS CATALYST UNDER ISOMERIZATION CONDITIONS TO FORM A REACTION PRODUCT CONTAINING NORMAL BUTANE, ISOBUTANE, AND ALKYL CHLORIDES, REMOVING SAID NORMAL BUTANE AND SAID ALKYL CHLORIDES FROM SAID ISOMERIZATION PRODUCT AND CONTACTING SAID ISOBUTANE AND AN OLEFIN WITH A SUPPORTED FRIEDEL-CRAFTS CATALYST UNDER ALKYLATION CONDITIONS TO ALKYLATE SAID ISOBUTANE WITH SAID OLEFIN.

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