MOLECULAR SHAPE SELECTIVITY OF EUO ZEOLITES

The micropores of the EUO zeolite consist of 10-membered ring (10-MR) channels with deep side-pockets circumscribed by 12-MRs. In decane iso merization and hydrocracking EUO zeolites crystallized in the presence of hexamethonium (HM) and dibenzyldimethylammonium (DBDMA) exhibit di fferent molecular shape selective properties. The catalytic sites of E UO specimens crystallized with DBDMA are located in more spacious cavi ties than those of EUO crystals synthesized with HM. This disparity in molecular shape selectivity is explained by a different location of t he framework aluminium atoms in the two materials, viz. by the absence of aluminium in the 10-MR channels in EUO-DBDMA. Such aluminium sitin g is in agreement with the location of the organic template cations in the pores of the as-synthesized zeolites suggested in literature and revealed by a molecular graphics modeling.