Patent GB-591631-A (GB)
Title: Process for the alkylation of alkylateable hydrocarbons
IPC: C07C2/60
Filed: 1944-11-09
Abstract: Alkylatable hydrocarbons are alkylated with olefins in a reaction zone containing a liquid aluminium halide-hydrocarbon complex, part of said hydrocarbons reacting with an aluminium halide to form said complex in the reaction zone, the reaction mass being removed, the complex separated from alkylate, and a major part thereof recycled to the reaction zone, fresh aluminium halide being introduced in an amount to maintain the aluminium halide content of the complex at about 60-85 per cent. by weight during the alkylation.  The fresh halide is preferably introduced by means of a carrier liquid, particularly part of the hydrocarbon reactant, which is passed through a pickup zone. Aluminium chloride is usually employed but other halides, for example the bromide, are also applicable.  The complex catalyst is formed by contacting the olefins with aluminium chloride in the presence of hydrogen halide, the paraffin reactants, and other hydrocarbons which may be in the charge.  It may be formed initially outside of the alkylation zone and charged thereto or the initial supply may be made in the alkylation zone by introducing aluminium chloride from a pickup zone or a slurry of the chloride in hydrocarbons such as isobutane, together with the olefin and hydrogen chloride.  An isobutane fraction may be fed with olefins, recycled paraffins, and hydrogen chloride to an alkylator having a stirrer and fed with the complex catalyst. Part of the isobutane and, if desired, part of the recycled paraffin first traverse a pickup vessel containing aluminium chloride, as such, admixed with other halides or on an adsorbent. When normal paraffins are present, the fuel may pass with hydrogen chloride and, if desired, hydrogen through the pickup vessel, when isomerization occurs.  Solvents for the complex, such as nitroparaffins, may be added thereto.  In a modification using a feed containing considerable n-butane, a separate isomerizer containing a packing, together with halides of the Friedel-Crafts' type if desired, is positioned between the pickup vessel and the alkylator. In examples: (1) an isobutane fraction is alkylated with butylenes, the complex catalyst being first prepared by passing the isobutane fraction through the pickup vessel and mixing the solution in the alkylator with hydrogen chloride and the butylene fraction.  The complex is separated and recycled until sufficient in quantity, when the pickup vessel is by-passed. Alkylation is now effected until analysis of the catalyst indicates that diversion of part of the isobutane through the pickup vessel is again necessary; (2) the catalyst is prepared outside the alkylator by agitating aluminium chloride, isobutane, and hydrogen chloride at 55-60 DEG C., while introducing ethylene for 6-8 hours, and decanting the complex.  It is used for alkylating isobutane with ethylene.  Analyses of the catalyst taken during the run are used to plot composition against time and to compare it with the yields of alkylate and the C6 content thereof, mainly 2, 3-dimethylbutane.  For high yields and optimum selectivity, the aluminium chloride content should be about 60-85 per cent., the inorganic chlorine content not less than 40, preferably 42-50 per cent., and the carbon content not more than 38, preferably 23-34 per cent.  The atomic ratio of inorganic chlorine to aluminium should be about 2.2-2.6:1, temperature about 10- 80 DEG C., preferably 40-60 DEG C., hydrogen chloride concentration not more than 3 mol per cent., and isobutane: ethylene molar ratio not less than 4 : 1.  The pickup temperature should not exceed about 83 and is generally 66-71 DEG C.ALSO:Alkylatable hydrocarbons are alkylated with olefins in a reaction zone containing a liquid aluminium halide-hydrocarbon complex, part of said hydrocarbons reacting with an aluminium halide to form said complex in the reaction zone, the reaction mass being removed, the complex separated from alkylate, and a major part thereof recycled to the reaction zone, fresh aluminium halide being introduced in an amount to maintain the aluminium halide content of the complex at about 60-85 per cent by weight during the alkylation.  The fresh halide is preferably introduced by means of a carrier liquid, particularly part of the hydrocarbon reactant, which is passed through a pick-up zone.  Paraffins of at least 4 carbon atoms, especially those having a tertiary carbon atom, may be alkylated with gaseous or liquid olefins, in particular isobutane with ethylene to yield 2,3-dimethylbutane. Naphthenes and aromatics may also be alkylated.  Aluminium chloride is usually employed, but other halides, for example the bromide, are also applicable.  The complex catalyst is formed by contacting the olefins with aluminium chloride in the presence of hydrogen halide, the paraffin reactants, and other hydrocarbons which may be in the charge.  It may be formed initially outside of the alkylation zone and charged thereto or the initial supply may be made in the alkylation zone by introducing aluminium chloride from a pick-up zone or a slurry of the chloride in hydrocarbons such as isobutane, together with the olefin and hydrogen chloride. An isobutane fraction may be fed with olefins, recycled paraffins and hydrogen chloride to an alkylator having a stirrer and fed with the complex catalyst.  Part of the isobutane and, if desired, part of the recycled paraffin first traverse a pick-up vessel containing aluminium chloride as such, admixed with other halides or on an adsorbent.  When normal paraffins are present, the feed may pass with hydrogen chloride and, if desired, hydrogen through the pick-up vessel, when isomerization occurs.  Products from the alkylator pass to a separator, the complex catalyst layer being recycled, apart from a minor portion which is withdrawn, and the hydrocarbon layer being fractionated to remove hydrogen chloride, and hydrocarbons such as propane, butane and isobutane, and recover the desired alkylate.  Solvents for the complex, such as nitroparaffins, may be added thereto.  In a modification using a feed containing considerable n-butane, a separate isomerizer containing a packing, together with halides of the Friedel-Crafts' type if desired, is positioned between the pick-up vessel and the alkylator.  Recycled butane and hydrogen chloride may be fed to the isomerizer with the feed.  In examples: (1) an isobutane fraction is alkylated with butylenes at about 50 DEG  C. and 17 atm., the complex catalyst being first prepared by passing the isobutane fraction through the pick-up vessel and mixing the solution in the alkylator with hydrogen chloride and the butylene fraction.  The complex is separated and recycled until sufficient in quantity, when the pick-up vessel is byepassed.  Alkylation is now effected until analysis of the catalyst indicates that diversion of part of the isobutane through the pick-up vessel is again necessary; (2) the catalyst is prepared outside the alkylator by agitating aluminium chloride, isobutane and hydrogen chloride at 55-60 DEG  C., while introducing ethylene for 6-8 hrs., and decanting the complex.  It is used for alkylating isobutane with ethylene at about 60 DEG  C. and 17 atm. with about 1.9 mol. per cent of hydrogen chloride present.  Analyses of the catalyst taken during the run are used to plot composition against time and to compare it with the yields of alkylate and the C6 content thereof, mainly 2,3-dimethylbutane.  For high yields and optimum selectivity, the aluminium chloride content should be about 60-85 per cent, the inorganic chlorine content no less than 40, preferably 42-50 per cent, and the carbon content not more than 38, preferably 23-34 per cent.  The atomic ratio of inorganic chlorine to aluminium should be about 2.2-2.6 : 1, temperature about 10-80, preferably 40-60 DEG  C., hydrogen chloride concentration not more than 3 mol. per cent, and isobutane: ethylene molar ratio not less than 4 : 1. The pick-up temperature should not exceed about 83 DEG  C. and is generally 66-71 DEG  C.