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

Grand canonical Monte Carlo (GCMC) simulations have been performed to inves tigate the localization and adsorption behavior of benzene and propylene, w hich 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 t hat the benzene and propylene molecules show different localization and ads orption behavior in the zeolite cavities. In the 10-MR channels, both benze ne and propylene show high localization. In the 12-MR supercages, the propy lene molecules cannot only almost fill all the possible positions in one su percage, but also can be steadily located in the short IO-MR conducts inter connecting the 12-MR supercages, where the benzene molecules are adsorbed c lose to three adsorption sites. By analyzing the location of benzene and pr opylene in ITQ-1, it can be deduced that the alkylation of benzene and prop ylene will happen mainly in 12-MR supercages. Moreover, a series of simulat ions 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 compound s. The results reveal that at low pressures, the loading of propylene is lo wer than that of benzene, which seems to be caused by the relatively unfavo rable potential interactions between propylene/zeolite and propylene/propyl ene. (C) 2001 Elsevier Science B.V. All rights reserved.