Insight into the Selection of the Post-Treatment Strategy for ZSM-5 Zeolites for the Improvement of Catalytic Stability in the Conversion of Methanol to Hydrocarbons

Desilication and dealumination are two common strategies to modify acidity and porosity of the ZSM-5 catalyst to enhance catalytic stability. However, the applicability of these strategies on the post treatment of specific ZSM-5 remains to be investigated. In this paper, a series of post-treated nanoZSM-5 was prepared using single dealumination and desilication or combining two strategies and the effects of the silicon-aluminum structure, porosity, and acidity on catalytic stability of methanol to hydrocarbons (MTH) have been comparatively studied. This study found that for nano-ZSM-5 whose diffusion limitation is not the main cause of deactivation, dealumination should be considered to optimize acidity and silicon-aluminum structure on the surface for the improvement of catalytic stability, while for micro-ZSM-5, desilication should be first applied to construct mesopores to reduce diffusion constraints, followed by dealumination to optimize acidity and surface silicon-aluminum structure to improve the catalytic stability.