Xylene isomerization process to exhaustively convert ethylbenzene and

Abstract

A new xylene isomerization process which is capable of converting ethylbenzene and non-aromatic exhaustively while selectively converting xylenes to thermal equilibrium in mixed EB/xylene feeds is proposed. The new process employs a two component catalyst system; each of the components contains a strong hydrogenation metal and a zeolite. The zeolite of each of the two components differs from the other in its selectivity for xylene isomerization and its capacity to deethylete ethylbenzene. That selectivity for xylene isomerization is described by xylene diffusion properties of the zeolite. In one embodiment of the invention, ZSM-5 of greater than 1 micron crystal size and an alpha value of greater than 100 in a first component and ZSM-5 of less than 1 micron crystal size and an alpha of less than 100 in a second catalyst component satisfy the diffusion properties which allow for the exhaustive conversion of ethyl benzene and non-aromatics and the selectivity for xylene isomerization of typical xylene isomerization feeds. In a preferred embodiment, the feed is cascaded over the first component and then the aforementioned second component.