ALKYLATION OF ISOBUTANE WITH 1-BUTENE ON ZEOLITE-BETA

Alkylation of isobutane with 1butene was carried out in the liquid pha se at 353 K on beta zeolite catalyst samples with varying framework Si /Al ratios and particle sizes. The specific external surface area dete rmined with nitrogen physisorption and t-plot analysis is the key para meter to rationalize alkylation activity and stability. The catalytic activity of zeolite beta samples with specific external surface areas smaller than ca 280 m(2) g(-1) suffers from intracrystalline diffusion al limitations. The critical particle size to avoid diffusional limita tions is estimated at 14 nm. In the absence of diffusional limitations , the alkylate yield obtained during the catalyst lifetime is proporti onal to the number of Bronsted acid sites in the zeolite and amounts t o ca 3 kg mole(-1), irrespective of the acid site density. The deactiv ation of the samples is explained by a site coverage model. (C) 1998 A cademic Press.