GB604278A - Improvements in or relating to the catalytic alkylation of isoparaffins and olefins - Google Patents

Abstract

Isoparaffins are alkylated with olefins using as catalyst a solution, saturated at about room temperature, of aluminium chloride in a complex of aluminium chloride and the alkylate and/or isoparaffin-olefin mixture, said solution containing no free solid aluminium chloride. The catalyst may be prepared by refluxing aluminium chloride with, for example, isobutane and ethylene or propylene at about <PICT:0604278/IV(b)/1> 110 DEG F. and sufficient pressure to liquefy, or with the alkylate, for example the C7-C8 fraction, followed by centrifuging or stratifying at about 70 DEG F. to remove solid or excess chloride. Aluminium chloride and C7-C8 alkylate are refluxed in vessel 1 and the catalyst, free from solid particles, pumped by line 5 to reactor 10. Isobutane and ethylene are fed from lines 14, 18 and alkylate, together with the excess alkylate from vessel 1, passes by line 22 to settler 24, separated catalyst being recycled by line 60, and the alkylate being in part recycled via line 30 and in part passed to a still 40 for recovery, separated isobutane being recycled by line 42. When necessary, part or all of this isobutane traverses a pick-up aluminium chloride drum 44. Spent catalyst is withdrawn via line 62 at a rate equal to the rate of addition of fresh. Alternatively, the catalyst may be formed in reactor 10 by reaction of the isobutane and ethylene with fresh aluminium chloride. Preferred conditions in reactor 10 are 90-180 DEG F. at pressures up to 400 lbs./sq. inch, contact times 20 mins. to 4 hrs., and molar ratios of paraffin: olefin of 1-10 : 1. Examples are given of the use of catalysts prepared from aluminium chloride and C7-C8 alkylate for alkylating isobutane containing 5 vol. per cent methyl chloride, with ethylene. The alkylate is compared with that obtained using catalysts containing free solid aluminium chloride, unsaturated complex or commercial aluminium chloride. The preferred catalyst of complex saturated with aluminium chloride has a C\sNH content of less than 39 per cent by weight. Specification 591,631 is referred to.