Study On The Alkylation Of Ethylbenzene To P-Diethylbenzene Over HZSM-5 Shape-selectivity Catalyst

Aimed at the technological process of the alkylation reaction of ethylbenzene with ethylene to p-diethylbenzene, in an industrial installation of product capacity 1500 t/y of p-diethylbenzene, the operating conditions and macrokinetics of the alkylation reaction in a fixed-bed reactor loading HZSM—5 molecular sieve modified by Mg were studied.In the fixed-bed reactor, the influence of temperature, ethylbenzene mass speed and reactant ratio on alkylation reaction were investigated respectively, and the results at different operation conditions were analyzed and discussed. The optimized parameters of reaction conditions were proposed. The kinetics equation and Arrhenius equation of o-, m-, p-diethylbenzene were investigated, and the reaction order, reaction rate constant, the activation energy and coefficient of Arrhenius equation were gotten. The kinetics equations are as follows.The results show that the concentration of o- and m-diethylbenzene increased simultaneously with p-diethylbenzene at various operating conditions. The reaction order, activation energy and coefficient of Arrhenius equation of o-, m-diethylbenzene were bigger than p-diethylbenzene, therefor the higher temperature and lower ethylbenzene mass speed, reactant ratio were not suitable to control the concentration of o- and m-diethylbenzene, and it was not a desirable result because the higher concentration of o- and m-diethylbenzene increased the difficulty of production separation, consequently, leading to the difficulty to attain highly pure p-diethylbenzene. The analysis of kinetics agreed well with practical production conditions.The rectified simulation and computation of alkylation reaction products were treated by the software HYSYS. The theoretical tray, reflux ratio and proper concentrations of o-, m-diethylbenzene were obtained according to the demand of product quality. It was shown that the concentration of o-, m-diethylbenzene should not be higher than 0.5%, otherwise highly pure p-diethylbenzene of 99% to attain was difficult.