Zeolite Beta as a catalyst for alkylation of benzene with ethylene: a deactivation study C. Flego * , G. Pazzuconi * , E. Bencini § , C. Perego * * EniTecnologie S.p.A. - Via Maritano, 26 - 20097 S. Donato Mil. (MI) - Italy § EniChem S.p.A. - Via Taliercio, 14 - 46100 Mantova - Italy Abstract Zeolite Beta is applied successfully as a catalyst for the alkylation of benzene (B) with ethylene (ET) to ethylbenzene (EB). Reaction conditions modify the performances and the lifetime of the catalysts. Under liquid phase operation, zeolite Beta shows any significant deactivation. However at lower reaction temperatures a decrease in both free acid sites and void channel volume is registered, due to carbonaceous compounds deposition. 1. INTRODUCTION In hydrocarbon processing the formation of carbonaceous deposits on the catalyst is the most frequent reason of deactivation. The role of the process conditions on the kinetics and the mechanism of coke precursors formation is important to control their amount and to favour the regeneration of the catalyst. Among petrochemical processes, the alkylation of benzene with ethylene to produce ethylbenzene is growing in the interest with the substitution of the industrially applied catalyst (i.e. AlCl 3 ) with solid acid materials such as zeolites (e.g. zeolite Beta) [1]. The importance of these catalysts is increasing, when their stability and regerability are verified. Under the reaction conditions usually applied in the liquid phase alkylation of B with ET, zeolite Beta shows almost no deactivation. In order to investigate the effects of reaction parameters on the coke formation very high space velocities (i.e. accelerated tests) had to be applied. In this paper zeolite Beta catalysts were characterized to evaluate the influence of the retained organic compounds on both acid sites density and void channel volume, after operation in accelerated tests at different reaction temperatures. 2. EXPERIMENTAL 2.1 Catalysts The catalyst (BF) is a zeolite Beta (SiO 2 /Al 2 O 3 =26) synthesised as reported in [2] and extruded with 50% wt alumina. Three zeolite samples are analysed, after operation under liquid phase in a Berty reactor at different reaction temperatures (170, 190 and 220°C). According to the reaction temperature, the samples are named B170, B190 and B220. 1.2 Physico-chemical characterization The amount of organic compounds deposited on the catalysts was evaluated by TG (ThermoGravimetric) analysis (20-800°C, 10°C/min, air flow). In order to determine the