GB639873A - Improvements in or relating to a process for producing mono-alkylbenzenes and the mono-alkylbenzenes resulting from said process - Google Patents

Abstract

Mono-alkyl benzenes are prepared by mixing benzene and a gaseous olefin in the presence of a Friedel-Crafts' catalyst at a pressure sufficient to maintain the liquid phase and at a temperature of 100-200 DEG , preferably 150-200 DEG C., and then passing the product to an evaporation zone at a lower pressure wherein lower boiling constituents are evaporated. Dry benzene, ethylene and aluminium chloride may be fed to an alkylator, the temperature rising, say, to 163 DEG C., and the pressure to 100-200, e.g. 150 p.s.i. The reaction liquor is then passed through an expansion valve to a flash column at about 1 p.s.i., benzene being vaporized, condensed and returned in part as reflux and in part to the alkylator. The bottoms from the column at about 115 DEG C. may be in part returned to the alkylator and in part to a separator where catalyst complex is separated and returned to the alkylator, except for a part used to dealkylate the poly-ethyl benzene. The separated alkylate is cooled to 20-30 DEG C., and further separated from complex. Polyethyl benzene, benzene and ethylene, in the presence of complex, are treated in a dealkylator giving a further conversion to ethyl benzene. Off-gases of the process comprising ethylene, ethyl chloride, hydrogen chloride and some benzene are treated in an absorber with polyethyl benzene prior to feeding the latter to the dealkylator.