Nestlike Hollow Hierarchical MCM-22 Microspheres: Synthesis and Exceptional Catalytic Properties

The synthesis and exceptional catalytic performance of nestlike hollow hierarchical MCM-22 microspheres (MCM-22-HS) were presented. The MCM-22-HSs were obtained by one-pot rotating hydrothermal synthesis using carbon black as a hard template via self-assembly combined hydrothermal crystallization. The shell of MCM-22-HS was hierarchically constructed by many flaky MCM-22 crystals. The Mo/MCM-22-HS exhibited significantly improved methane conversion, yield of benzene product and catalyst lifetime for methane dehydroaromatization as a model reaction. The exceptional catalytic performance was attributed to the hollow and hierarchical structure. Faster transfer of Mo species because of the existing mesopores and higher dispersion of Mo species brought by the higher external surface of the Mo/HMCM-22-HS lead to generation of more catalysis active sites and high benzene yield. The sites associated with catalyst deactivation could also be reduced, contributing to improvement of the catalyst lifetime. Both the hierarchical and hollow structure is favorable for the diffusion of larger molecule product, probably contributing to significant improvement of the catalyst lifetime. This work demonstrated the potential applications of hollow hierarchical microsphere structure in catalytic engineering.