The localization and adsorption of benzene and propylene in ITQ-1 zeolite: grand canonical Monte Carlo simulations

Abstract

Grand canonical Monte Carlo (GCMC) simulations have been performed to investigate the localization and adsorption behavior of benzene and propylene, which are involved in the cumene synthesis process, in purely siliceous MWW zeolite (ITQ-1). From the mass clouds of GCMC simulations, it can be seen that the benzene and propylene molecules show different localization and adsorption behavior in the zeolite cavities. In the 10-MR channels, both benzene and propylene show high localization. In the 12-MR supercages, the propylene molecules cannot only almost fill all the possible positions in one supercage, but also can be steadily located in the short 10-MR conducts interconnecting the 12-MR supercages, where the benzene molecules are adsorbed close to three adsorption sites. By analyzing the location of benzene and propylene in ITQ-1, it can be deduced that the alkylation of benzene and propylene will happen mainly in 12-MR supercages. Moreover, a series of simulations have been performed to predict the adsorption isotherms of benzene and propylene at 315 K and 0–1.4 kPa. The results for benzene generally are in agreement with the trend from experiments on a series of aromatic compounds. The results reveal that at low pressures, the loading of propylene is lower than that of benzene, which seems to be caused by the relatively unfavorable potential interactions between propylene/zeolite and propylene/propylene.