MnOx/ZrO2-Cr2O3催化剂的结构及催化苯甲酸甲酯加氢性能

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

  • 摘要: 采用并流共沉淀和浸渍法制备了MnOx/ZrO2-Cr2O3催化剂。利用X射线衍射(XRD)、N2物理吸附(BET)、氢气程序还原(H2-TPR)、X射线光电子能谱(XPS)等手段对催化剂的结构和表面性质进行了表征。结果表明,Cr的引入导致ZrO2晶型由m-ZrO2t-ZrO2转变,随着Cr含量的增加,ZrO2-Cr2O3复合氧化物的比表面积逐渐增大,平均孔径逐渐降低,孔结构也发生变化;Mn的引入会造成ZrO2-Cr2O3复合氧化物中Cr的迁移,同时也有利于ZrO2晶型由m-ZrO2t-ZrO2转变,从而引起催化剂比表面积、孔结构的变化;含4% Mn和2.5% Cr的MnOx/ZrO2-Cr2O3催化剂对苯甲酸甲酯加氢反应的单程转化率和选择性分别达到93.86%和86.05%。

     

    Abstract: MnOx/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 MnOx/ZrO2-Cr2O3 catalysts containing 4% Mn and 2.5% Cr for methyl benzoate hydrogenation were 93.86% and 86.05%, respectively.

     

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