Preparation of Cu-based Hierarchical Pore ZSM-5 Zeolite Single Crystals and Their Catalytic Properties for Nitrobenzene Hydrogenation

In order to solve the problem of irreversible damage of zeolite framework in the process of intracrystalline hierarchically porous creation, a single crystal of silica-alumina zeolite ZSM-5 (OMMS-ZSM-5) with hierarchically ordered macro-meso-microporous structure was successfully bottom-up in situ synthesized by using ordered macro-mesomicroporous carbon with anti-opal structure as a hard template, which possesses high external specific surface area (195.8 m(2)/g) and pore volume (0.27 cm(3)/g). In addition, a series of Cu-OMMS-ZSM-5 catalysts with different Cu loadings (mass fraction: 1%, 5%, 10%) was prepared by impregnation method using OMMS-ZSM-5 as a carrier to investigate the catalytic ability of different metal loading catalysts in the liquid-phase hydrogenation reaction of nitrobenzene. The physical and chemical properties of the prepared catalysts were comprehensively characterized by SEM, TEM, XRD, NMR, N-2 adsorption-desorption, NH3-TPD, XPS and H-2-TPR tests, which shows that the Cu elements are highly dispersed in the form of CuO, and the conversion of nitrobenzene reaches up to 96.8% and the selectivity of aniline reaches 99.3% when the loading is 9.58% (mass fraction). Compared with the Cu-based micron ZSM-5 zeolite catalytic material, the aniline selectivity and the nitrobenzene conversion of Cu-OMMS-ZSM-5 are improved by 32.4% and 26.1%, respectively, and the high catalytic activity is maintained after three cycles.