ALKYLATION OF TOLUENE WITH METHANOL ON ALUMINA-PILLARED MONTMORILLONITE - SUPPRESSION OF DEACTIVATION BY CONTROL OF THE LATERAL SPACINGS OF PILLARS

Alkylation of toluene by methanol was carried out using alumina-pillared montmorillonite with different pillar populations or different lateral spacing of pillars. The main products were xylenes (80-83%) and trimethylbenzenes (15-20%). The xylene selectivity increased slightly with time on stream at the expense of the trimethylbenzene selectivity. The isomeric distribution was approximately 40, 25 and 35% for o-, m-, and p-xylene, and 22, 74 and 4% for 1,2,3-, 1,2,4- and 1,3,5-trimethylbenzene. The initial activity, i.e., toluene conversion after 30 min of reaction, was higher on montmorillonite with large pillar population than with small pillar population. The activity decreased with time on stream due to coke deposition. The rate of deactivation, evaluated from the ratio of the toluene conversion after 5 h of reaction to that after 30 min, was larger for large lateral pillar spacing than for small lateral spacing. The suppression of deactivation is understood in terms of the relative dimension of pores and coke precursors.