DIFFUSION OF AROMATIC-HYDROCARBONS IN H-ZSM-5, H-BETA, AND H-MCM-22 ZEOLITES

Using Fourier transform infrared spectrometry, the intrinsic diffusion coefficients of benzene, toluene, ethylbenzene, m-xylene, and o-xylen e in H-ZSM-5, H-Beta, and H-MCM-22 were measured at different temperat ures. By means of a microscopic model to describe the molecular diffus ion in zeolites and the use of the transient state theory, the self-di ffusion coefficients of molecules in zeolites with straight channels w ere calculated. The experimental results obtained are compared with th ose calculated theoretically, and they are discussed on the basis of t he framework structure of the studied zeolites.