DIFFUSION OF XYLENES AND ETHYLBENZENE IN A LINDE 13X ZEOLITE

Diffusion coefficients of four molecules (o, m, p xylene and ethylbenzene) in a Linde 13X zeolite were determined at 150° to 190°C by the Glueckauf method, using hydrogen as a transport gas and overall activation energies (EP) for diffusion were derived. Various potential energy expressions [Lennard-Jones 6—12 (L —J), Buckingham 6-exp (B), Kitaygorodsky (K)] were used to calculate the minima of the total potential energy (EO) corresponding to interaction between the organic molecules and the twelve-membered ring of oxygen atoms blocking the access to the zeolite supercages. Activation energies for diffusion in the bulk (supercages) of the zeolite, EB, were taken as the difference EB = EP − EO. According to the practical application of the X-zeolite in the separation of p-xylene from the other three substances, this molecule has the lowest diffusion coefficient and lowest activation energy for diffusion in the bulk. © by Akademische Verlagsgesellschaft