ABSTRACT
Liquid-phase processes based on an aluminium chloride catalyst have been developed by many companies and achieved great importance. Ethylbenzene is contained in C8 aromatic streams arising from catalytic reforming, and absorption and distillation processes have been developed for its recovery. In the non communist countries and the former Eastern bloc the liquid phase process accounts for nearly half of total ethylbenzene capacity. The presence of sulphur, toluene, xylenes and paraffins in the benzene feed are undesirable as they lead to unwanted by-products. The separation requires three columns. Unreacted benzene is recovered overhead from the first column, which is operated at slightly elevated pressure, and recycled. Transalkylation and alkylation occur simultaneously, and the heat generated by the exothermic reaction is used to generate steam. The Alear vapour-phase process is designed to utilize refinery and coke-oven gas streams containing 8–10 mole% of ethylene. Ethylbenzene is less toxic than benzene, but it has an irritating effect on the eyes, skin and respiratory tract.
