Optimal feed ratio of benzene–propylene binary mixtures for alkylation in ZSM-5 by molecular simulation

The adsorption behavior of benzene/propylene mixtures in ZSM-5 zeolite at supercritical conditions has been studied by using Monte Carlo simulation. To guarantee that our simulation is performed at supercritical conditions, we used the Peng–Robinson equation to calculate phase diagrams of benzene–propylene mixtures at different feed ratios of benzene/propylene. Based on the experimental data at supercritical conditions where the optimal reaction ratio of benzene/propylene is 1:1, we predicted that the optimal feed ratio (Rf) of benzene/propylene is 5:1, in which the equilibrium ratio of benzene/propylene in ZSM-5 is 1:1. At the optimized feed ratio of Rf = 5.0, we also calculated the adsorption behavior of benzene/propylene in ZSM-5 at other conditions, such as gas, vapor and liquid phase conditions. We observed that the near supercritical condition is more suitable for the benzene alkylation with propylene in ZSM-5 than other conditions. Therefore, we recommend that the feed ratio of benzene/propylene of 5:1 at near supercritical condition is an optimal operative condition for synthesis of cumene via the benzene alkylation with propylene in ZSM-5.