Abstract: Ni/yMnO_x-ZrO₂ composite oxides with different Mn/Zr molar ratios were synthesized by planetary ball milling method, and a series of Ni/yMnOx-ZrO2 catalysts were prepared by loading nickel on them.The physicochemical properties of the catalysts were characterized by X-ray diffraction, NH₃ temperature programmed desorption, pyridine infrared, N₂ physical adsorption-desorption, and hydrogen temperature programmed reduction.The catalytic performance of Ni/yMnO_x-ZrO₂catalysts in the hydroconversion of guaiacol was investigated. The results showed that the doping of Mn promoted the formation of weak acid and medium-strong acid on Ni/yMnO_x-ZrO₂ catalysts, which was beneficial to the generation of cyclohexanolviathe reaction path of phenol intermediate formed via guaiacoldemethoxylation.Both increasing the reaction temperature and prolonging the reaction time were beneficial to improve the yield of cyclohexanol, but it could lead to excessive hydrogenation of cyclohexanol to cyclohexane.When the molar ratio of Mn/Zr was 0.20, the Ni/0.20MnO_x-ZrO₂ catalyst showed excellent catalytic performance. Under the reaction conditions of 260 ℃, 2.0MPa and 1.5 h, the conversion of guaiacol and the selectivity of cyclohexanol were 100% and 63.5%, respectively.

Key words: composite oxide, Ni-based catalyst, ZrO₂, Mn doping, guaiacol, cyclohexanol