Diffusion of Trimethylbenzenes and Xylenes in Zeolites with 12- and 10-Ring Channels as Catalyst for Toluene-Trimethylbenzene Transalkylation

A molecular dynamics study of the diffusion of trimethylbenzene (TMB) and xylene molecules involved in toluene and TMB transalkylation reaction has been performed over 6 different pure-silica zeolites, containing 10- and 12-ring channels: BOG, MSE, IWR, SFS, SOF, and UWY. The shape selective properties of these six frameworks have been tested using two different loadings: one loading characteristic of the early stage and another of the late stage of the reaction. The collected data explains the diffusion behavior of these molecules in the zeolite frameworks and allows researchers to obtain trends and also rationalize their performance as candidates for the selective production of p-xylene during transalkylation of toluene and TMB. UWY appears a promising zeolite that allows the reaction of the TMBs in the 12-ring channels, is able to host the transition states, and favors the preferential diffusion of p-xylene in the 10-ring channels.