Chemical Engineering Journal, Vol.306, 1071-1080, 2016
The effect of alkylation route on ethyltoluene production over different structural types of zeolites
Ethyltoluenes (ET) synthesis via different alkylation routes; toluene with ethanol and ethylbenzene (EB) with methanol, was investigated over zeolites with three-dimensional (3D) pore system i.e. SSZ-33, TNU-9, ZSM-5, IM-5, and one-dimensional zeolite MOR in a fluidized-bed reactor in the temperature range 250-350 degrees C for reaction times of 5-20 s. Alkylation of toluene with ethanol provided higher yields and selectivities to ethyltoluenes over all zeolites. The maximum ET yield achieved for toluene ethylation was 13.7 wt.% using IM-5 and ZSM-5 whereas 12.5 wt.% was obtained in EB methylation over SSZ-33. SSZ-33 provided the highest ET-selectivity of similar to 50% due to the combine effect of its 3D topology and 12-ring channels. In contrast to ET selectivity, p-ethyltoluene selectivity was almost the same, similar to 26%, irrespective of the zeolite topology. Kinetic studies of toluene ethylation over the zeolites were conducted using power law coupled with time-on-stream deactivation model. A satisfactory correlation between experimental data and the model result was achieved. The activation energy of the various zeolites used for the alkylation of toluene to ET decreased in the order: IM-5 (58.2 kJ/mol) > SSZ-33 (39.7 kJ/mol) > TNU-9 (27.3 kJ/mot) > MOR (20.2 kJ/mol) > ZSM-5 (17.0 kJ/mol) which was explained by different acid strength and nature of the zeolites. (C) 2016 Elsevier B.V. All rights reserved.
Keywords:Ethyltoluenes;Alkylation;Toluene;Ethylbenzene;Ethanol;Methanol;Zeolite topology;Kinetic study