Inactivation of external surface of ZSM-5: Zeolite morphology, crystal size, and catalytic activity

The enhancement of the para selectivity feature of the zeolite by inactivation of the external surface was studied. The morphology and crystal size play a major role in deciding the extent of modification required to achieve a predesired para selectivity. The extent of modification was higher for the zeolite batches containing smaller, spheroidal shaped crystals, while it was lower for the batches having longer, oblong shaped crystals. Any covering of the oblong crystals by foreign particles such as silica enhances the extent of inactivation required to achieve a specific para-compound selectivity. (C) 1996 Academic Press, Inc.