Effects of Surface, Interface, and Defect on Zeolite Catalysis Probed by a 3D Anisotropic Model

Zeolite catalysts are characterized by complex surface, interface, and defect structures, which are tightly related to diffusion and subsequent reaction in these catalysts. Herein, we develop a three-dimensional anisotropic model to describe anisotropic diffusion, surface/interface barriers, and reactions in zeolites with rich defects. Benzene alkylation with ethylene catalyzed by ZSM-5 zeolite is taken as the model reaction system. The results show that diffusion anisotropy largely affects the apparent reaction rate of a zeolite catalyst, indicating that diffusion anisotropy should be accounted for. Surface and interface diffusion barriers play an important role when diffusion limitation is strong in zeolites, and it is necessary to regulate surface and interface structures in these cases. Introducing defects into zeolites is favorable. The optimal size, volume, and spatial distribution of defects are obtained to balance diffusion and reaction. This work provides a powerful model and some useful guidance for the optimal design of zeolite catalysts.