助剂对Ni/SiO2催化剂微观结构及二硝基甲苯催化加氢性能的影响

采用等体积浸渍法制备了负载型Ni/SiO₂催化剂，研究了Ce、Zr、La、Co和Fe助剂对催化剂微观结构及其催化二硝基甲苯（DNT，C₆H₃CH₃（NO₂）₂）加氢制备甲苯二胺（TDA，C₆H₃CH₃（NH₂）₂）性能的影响。通过XRD，BET，H₂-TPD、H₂-TPR和XPS技术对催化剂进行了表征。结果表明，助剂的引入促进了Ni物种在载体表面的分散，减小了Ni晶粒的尺寸，使得NiO晶粒更易还原。添加La、Fe和Zr助剂增加了有效的Ni活性中心数，有利于催化活性的提高，其中，添加La助剂制备的催化剂催化性能最优，DNT转化率和TDA选择性分别为98.1%和99.1%。但Co和Ce助剂的加入降低了化学氢吸附量，使得有效的Ni活性中心数降低，降低了催化剂的催化活性。

Influence of Addictives on Ni/SiO2 Catalyst Microstructure and the Performance of Dinitrotoluene Hydrogenation

Ni/SiO₂ catalysts were prepared by incipient wetness impregnation method. The effect of promoters about Ce, Zr, La, Co and Fe on catalysts microstructure as well as the performance of dinitrotoluene hydrogenation to toluenediamine were also studied. The catalysts were characterized by XRD, BET, H₂-TPD, H₂-TPR and XPS. The results showed that the addition of addictives can promote the dispersion of nickel species and decrease Ni particle size and make easier for NiOreduction. The additives of Zr, La and Fe increasing the Ni active center improved the catalytic performance, especially the addition of La with the conversion of DNTand the selectivity of TDA can reach 98.5% and 99.1%, respectively However, the addition of Co and Ce addictives caused the decreasing of the amount of chemical adsorption and Ni specie on the catalyst surface. It also led the Ni active center decreasing which is negative for catalytic performance.