Catalytic aromatization of methanol over post-treated ZSM-5 zeolites in the terms of pore structure and acid sites properties

The effects of zeolite structure and acidity on catalyst life of methanol to aromatic (MTA) reactions have been investigated using a number of MFI zeolites with different degrees of mesoporosity and acidity, which were obtained via the post-synthetic desilication with tetrapropylammonium hydroxide. The influence of the post -synthesis on the pore characteristics of the ZSM-5 zeolites were studied by combined N-2 adsorption/desorption and temperature programmed desorption of n-octane (n-octane-TPD) techniques. The acidity were quantitatively analysed by NH3-TPD and acetonitrile-TPD. The results indicated that the desilication increased the mesoporosity and decreased the strong acid density, which inhibited the coke formation and then increased the catalytic stability. NH3-TPD and FT-IR techniques were used to characterize the changes of the partially deactivated catalysts. It suggests that deactivation and the decrease of aromatic selectivity are associated with the reduction in the strong Bronsted sites. (C) 2017 Elsevier B.V. All rights reserved.