Controllable Multicomponent Co‐Assembly Approach to Ordered Mesoporous Zirconia Supported with Well‐Dispersed Tungsten Oxide Clusters as High‐Performance Catalysts

Abstract

AbstractZirconia supported WOx clusters with high acid strength and good stability are important solid acid catalysts in many reactions. However, conventional synthetic methods such as incipient‐wetness impregnation and co‐precipitation usually result in the products with low catalytic activity due to low surface area, uncontrollable and non‐homogeneous distribution of tungsten species. In this study, a facile multicomponent co‐assembly approach was utilized to straightforwardly synthesize ordered mesoporous WOx/ZrO2 composites (OMWZr) with mesopore size over 17 nm, pore volume of 0.13–0.18 cm3/g and surface area of 27.3–41.7 m2/g. The materials were composed of robust crystalline ZrO2 skeleton and well‐dispersed WOx clusters (polytungstates) in framework under the optimized conditions. The tungsten species were well stablized by the crystallized skeletons of mesoporous ZrO2, which can inhibit the growth of tetragonal ZrO2 but facilitate crystallization of monoclinic ZrO2. The states of tungsten species (monotungstates, polytungstates and crystalline WO3) can be precisely adjusted by their doping amount in framework and calcination temperature as well, which can further tune the surface acidity of OMWZr composites. Owing to the existence of numerous active surface WOx clusters generated over exposed surface of mesoporous ZrO2, the OMWZr catalysts not only show great spatial homogeneity of accessible Brønsted acid sites and feasible mass diffusion during catalytic reactions, but also display outstanding acid‐catalytic performance over hydrolysis reactions of benzaldehyde dimethyl acetal. The catalyst can be reused for more than 10 cycles, without reduction of catalytic activity and selectivity to benzaldehyde.