单斜相与四方相混合晶相组成ZrO2负载镍催化剂催化顺酐选择性加氢

通过调控水热法制备条件制备同为单斜相和四方相混合晶相组成、但织构性质和表面结构性质不同的两种ZrO_2载体,采用浸渍法制备镍质量分数为10%的Ni/ZrO_2催化剂,考察不同反应温度(150～240)℃]和氢气压力(3～7)MPa]条件下两种ZrO_2载体负载镍催化剂的顺酐加氢性能。采用XRD、H_2-TPR、H_2-TPD和拉曼光谱等对催化剂进行表征。结果表明,与镍物种发生较强相互作用的ZrO_2负载镍催化剂具有较高的■键加氢活性与选择性,几乎没有■加氢活性,在所考察的反应温度和反应压力范围,催化剂上丁二酸酐选择性均高于95.1%,γ-丁内酯选择性均低于4.9%。与之不同,与镍物种发生较弱相互作用的ZrO_2负载镍催化剂具有较弱的■键加氢活性,然而,该催化剂表现出一定的■加氢活性,并且其■加氢活性随反应温度或反应压力的提高而显著提高。在反应温度240℃、氢气压力5 MPa条件下,γ-丁内酯选择性高达60.6%。推测晶相组成相似的两种ZrO_2载体负载镍催化剂明显的■加氢性能差异与其表面结构性质不同有关。

Selective hydrogenation of maleic anhydride catalyzed by supported nickel catalysts on ZrO2 of monoclinic and tetragonal mixed crystal phase

Two kinds of ZrO₂ supports,both composed of monoclinic and tetragonal phases,but with different texture properties and surface structures,were prepared by adjusting hydrothermal conditions.Ni/ZrO₂ catalysts mith Ni mass fraction of 10% were prepared using an impregnation method and were characterized by XRD,H₂-TPR,H₂-TPD and Raman techniques.Their catalytic performances in maleic anhydride hydrogenation were tested under different reaction temperature (150-240) ℃ and H₂ pressure (3-7) MPa.Results showed that Ni/ZrO₂ catalyst with strong interaction of nickel species and ZrO₂ support had higher C=C hydrogenation activity,whereas it had almost no C=O hydrogenation activity.Within the range of reaction temperature and H₂ pressure investigated,the selectivity of the catalyst for succinic anhydride was above 95.1%,correspondingly,the selectivity of γ-butyrolactone was less than 4.9%.Ni/ZrO₂ catalyst with weaker interaction of nickel species and ZrO₂ support had lower C=C hydrogenation activity,whereas it exhibited C=O hydrogenation,and the C=O hydrogenation activity increased significantly with rise of reaction temperature and H₂ pressure.The selectivity towards γ-butyrolacetone was as high as 60.6% at reaction temperature of 210 ℃ and H₂ pressure of 5 MPa.It was inferred that the obvious difference of C=O hydrogenation activity of two ZrO₂ supported nickel catalysts was related to the different surface structure properties of ZrO₂ supports.