Liquid-Phase Alkylation of Benzene with Light Olefins Catalyzed by β-Zeolites

The catalytic performance of zeolite β in the liquid-phase alkylation of benzene is compared with that of other solid catalysts. Zeolite β is more active and more selective than zeolite Y in the alkylation with propylene and ethylene to cumene and ethylbenzene (EB). In the alkylation with propylene the overall selectivity of β is higher than that of the traditional "solid phosphoric acid." The catalytic activity is affected by the composition and the particle size of zeolite β samples. Decreasing the framework Al content, by direct synthesis or by partial substitution of Al for B, produces a decrease in both conversion and selectivity in cumene and EB synthesis. A hypothesis to explain this behavior is given. The catalytic activity of zeolite β is limited by intraparticle diffusion, as evidenced by the decreased activity corresponding to the particle size increase.