High yield styrene prodn. - by toluene dehydro:dimerisation and heating with ethylene over chromium, tungsten and alkali metal oxide(s)

摘要

Styrene is prepd. by dehydrodimerisation of toluene, followed by heating the prod. at 300-600 degrees C in the presence of ethylene and a catalyst composed of 1.5-5.2 wt. % Cr oxide, 4.0-6.1 wt.% W oxide, 0.1-0.7 wt.% an alkali metal oxide and the balance silica or silica-alumina. Styrene is obtd. in a high yield, e.g. 78-80 wt.%, as calculated for the converted dehydrodimerisation prods. and ethylene, by a simplified process not involving separation or hydrogenation of stilbene. In an example, toluene and air are passed at 490 degrees C over Bi oxide on corundum. Dibenzyl and stilbene are recovered by rectification and passed with ethylene at 490 degrees C over oxides of Cr, W and Na on silica. Styrene of purity 99.9% is recovered by rectification. Yield = 72 wt.% based on coverted dibenzyl/stilbene and ethylene.