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Abstract: The catalytic synthesis of ethylbenzene by alkylation of benzene with diethyl carbonate was carried out over HZSM-5 with Si/Al ratios from 50 to 250. The catalysts were characterized by XRD, SEM, 29Si and 27Al MAS-NMR, NH3-TPD and pyridine IR techniques. HZSM-5 with a Si/Al ratio of 200 exhibited the best benzene conversion and ethylbenzene selectivity because of its ideal acid strength. Strongly acidic sites may lead to an excessive decomposition of diethyl carbonate. The effects of temperature, feed ratio, WHSV and time-on-stream on catalytic activity and product selectivity were studied, and a possible mechanism is presented. [Copyright &y& Elsevier]