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 inac tivation of the external surface was studied. The morphology and cryst al size play a major role in deciding the extent of modification requi red to achieve a predesired para selectivity. The extent of modificati on was higher for the zeolite batches containing smaller, spheroidal s haped crystals, while it was lower for the batches having longer, oblo ng shaped crystals. Any covering of the oblong crystals by foreign par ticles such as silica enhances the extent of inactivation required to achieve a specific para-compound selectivity. (C) 1996 Academic Press, Inc.