Kinetic analysis of benzene ethylation over ZSM-5 based catalyst in a fluidized-bed reactor

Benzene ethylation has been investigated over fresh ZSM-5 based catalyst in a riser simulator that mimics the operation of a fluidized-bed reactor. Experimental runs for the kinetic study were carried out at four different temperatures (300, 325, 350 and 400 °C) for reaction times of 3, 5, 7, 10, 13, and 15 s. Benzene to ethanol (B/E) mole ratio was varied from 1:1 to 3:1. Benzene conversion, ethylbenzene yield and diethylbenzene yield were found to increase with reaction temperature and time for the different temperatures. The maximum benzene conversion of 16.95% in which the main products were ethylbenzene, diethylbenzene and other hydrocarbon as by-products was obtained over the fresh catalyst at 400 °C. The experimental results were modeled using quasi-steady-state approximation with catalyst deactivation function based on two different models. Kinetic parameters for benzene ethylation and ethylation of ethylbenzene with ethanol were estimated by non-linear regression analysis. The apparent activation energy of benzene ethylation (E₁) was found to be higher than the value for ethylbenzene ethylation (E₂). In addition, the effect of feed ratio (B/E) on the activation energies and products distribution was also investigated in this study.