1995 Volume 21 Issue 6 Pages 1120-1126
By using dealuminated and Ba-ion exchanged mordenites, the effect of the number and strength of acid sites on the rate of deactivation in methanol conversion has been examined. Although H-mordenite with a SiO2/Al2O3 ratio of 15 was seriously deactivated by deposition of coke, a decrease in the rate of deactivation was observed on dealuminated mordenites with a SiO2/Al2O3 ratio of more than 164 and on doubly modified mordenites. From NH3-TPD spectra, the number of strong acid sites in these modified mordenites was less than 0.5 per unit cell. Since an average distance between neighboring strong acid sites, calculated from this acid amount, is longer than the molecular diameter of polyalkylbenzene, it was supposed that suppression of deactivation is due to the reduction of adjacent strong acid sites for polymerization of polyalkylbenzenes.