Role of surface pockets on MCM-49 structure in the alkylation of hydroquinone with tert-butanol

A series of MCM-49 catalysts with different Si/Al ratios were prepared and characterized by XRD, XRF, 27Al MAS NMR, BET, and SEM. The overall and external surface acidity of the catalysts were measured by temperature-programmed desorption of both small- and large-base probe molecules (NH3 and 2,6-di-tert-butyl-pyridine), as well as by model acid-catalyzed reactions, such as cumene cracking and 1,3,5-tri-tert-butyl-benzene dealkylation, and compared with those of ZSM-5 and USY zeolites. The strong external acid sites on the surface pockets of MCM-49 play an important role in the alkylation of hydroquinone with tert-butanol. MCM-49 catalyst with a Si/Al ratio of 20 exhibits good activity and selectivity for the alkylation reaction, and it is more reusable than mesoporous molecular sieves such as AlSBA-15 and MSU-S(BEA) due to the higher thermal and hydrothermal stability of the crystalline zeolite framework.