GB640040A - 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 produced by supplying simultaneously and in parallel flow to each of two alkylators 1 and 2 containing alkylation liquor including an aluminium chloride-aromatic hydrocarbon complex, a stream of benzene, introducing to alkylator 2 a gaseous olefin, e.g. ethylene, propylene or butylene, in such an amount as to maintain a reaction temperature of 80-100 DEG C., and to alkylator 1 an amount of said olefin in excess thereof, continuously withdrawing liquor from alkylator 1, cooling, contacting with olefin off gas from 1 and 2, withdrawing alkylated liquor from 1 and 2, separating it into benzene, mono-alkyl, and poly-alkyl benzene fractions, and returning poly-alkyl benzene to alkylator 2. A promoter, e.g. 0.3 per cent hydrogen chloride or ethyl chloride, may be added to the dry benzene. Each alkylator operates at 80-100 DEG C. and substantially atmospheric pressure, and is connected to a separator which separates and returns the catalyst complex. At equilibrium, 10-30 per cent of the total olefin is fed to alkylator 2. The off-gases are scrubbed with cooled reaction liquor, at 40-50 DEG C., with benzene, and finally with poly-alkyl benzene. Alkylate liquor from the separators is water and alkali washed prior to fractionation. Fresh aluminium chloride is added to the circulating complex in both alkylators.