The ZnO supported on -Al2O3, SiO2, MCM-41, and -zeolite were prepared and examined in the hydrogenation of methyl benzoate (MB). ZnO supported on -Al2O3 had a higher activity than ZnO. ZnO/-Al2O3 modified with 23 ppm lithium had a high catalytic activity (97%) and high selectivity to benzaldehyde (BD, 87%) in a fixed-bed reactor at atmospheric pressure and 400℃. Chromium oxide modified ZnO/ -Al2O3 also had a high selectivity to BD. Hydrogenolysis of MB occurred over copper modified catalysts. X-ray powder diffraction (XRD) revealed that in the ZnO/-Al2O3 catalysts, the ZnO, ZnAl2O4 and -Al2O3 phases exited mainly, the border of ZnO and ZnAl2O4 might be important for the hydrogenation of MB to BD. XPS and FT-IR revealed that the chemical environment of ZnO on the ZnO/-Al2O3 catalyst is different to ZnO and other supported ZnO catalysts, which gives the ZnO/-Al2O3 catalyst having a higher activity than ZnO or ZnO on SiO2, MCM-41 or -zeolite. The presence of third metal (Li, Cr or Cu) oxide in ZnO/-Al2O3 could change the electronic structure of Zn and the chemical phenomena of Zn-Al in catalyst and lead to change of the catalytic performance.

A series of supported ZnO catalysts were prepared by a novel method, hydrothermal-impregnation-precipitation (HIP). The activities of catalysts were tested for hydrogenation of methyl benzoate (MB). ZnO supported on MCM-41 behaves much higher activity than that on -Al2O3, -zeolite and SiO2. Changing the loading of ZnO on MCM-41 can adjust the depth of hydrogenation of MB, and high loading of ZnO is available for the hydrogenolysis of MB to benzene. XRD, FT-IR and N2 absorption were used to reveal that zinc oxide incorporated into the pore channels of MCM-41 in single or double molecular ZnO layer. After supporting 10%ZnO on MCM-41 by HIP, the structure of MCM-41 is unchanged, its pore diameter decreases from 3.14 to 2.62nm.