The structure and hydrogenation performance for methyl benzoate of MnO_x/ZrO₂-Cr₂O₃ catalyst

MnO_x/ZrO₂-Cr₂O₃ catalysts were prepared by cocurrent coprecipitation and impregnation. The structure and surface properties of the catalyst were characterized by X-ray diffraction (XRD), N₂ physical adsorption (BET), hydrogen temperature programmed reduction (H₂-TPR), and X-ray photoelectron spectroscopy (XPS). These results showed that the addition of Cr led to the transformation of ZrO₂ crystal form from m-ZrO₂ to t-ZrO₂. With the increase of Cr content, the BET of the composite oxide ZrO₂-Cr₂O₃ increased gradually, the average pore size decreased and the pore structure also changed. The impregnation of Mn caused the migration of Cr in the ZrO₂-Cr₂O₃ composite oxide, and promoted the transformation of the ZrO₂ crystal form from m-ZrO₂ to t-ZrO₂, the BET and pore structure of the catalyst changed also. The conversion and selectivity of MnO_x/ZrO₂-Cr₂O₃ catalysts containing 4% Mn and 2.5% Cr for methyl benzoate hydrogenation were 93.86% and 86.05%, respectively.