Selective hydrogenation of benzene to cyclohexene over nanocomposite Ru-Mn/ZrO2 catalysts

A series of Ru-Mn catalysts with different Mn contents were prepared by coprecipitation, and their catalytic performance, using nanoscale ZrO2 as a dispersant, for the selective hydrogenation of benzene to cyclohexene was investigated. The catalysts were characterized using X-ray diffraction, transmission electron microscopy, N2 physisorption, X-ray fluorescence, atomic absorption spectroscopy, and Auger electron spectroscopy. The results confirmed that the Mn existed as Mn3O4 on the Ru surface. The Mn3O4 reacted with ZnSO4 to form an insoluble [Zn(OH)2]3(ZnSO4)(H2O)3 salt, which was readily chemisorbed on the Ru surface. This chemisorbed salt played a key role in improving the cyclohexene selectivity over the Ru catalyst. The cyclohexene yield of 61.3% was obtained over the Ru-Mn catalyst with the optimum Mn content of 5.4%. This catalyst had good stability and excellent reusability.

摘要采用共沉淀法制备了一系列不同 14;Mn 14;含量的纳米 14;Ru-Mn 14;催化剂, 14;考察了纳米 14;ZrO2 14;作分散剂时它们催化苯选择加氢制环己烯的反应性能, 14;并采用 14;X 14;射线衍射、透射电镜、N2 14;物理吸附、X 14;射线荧光、原子吸收光谱和俄歇电子能谱等手段对催化剂进行了表征. 结果表明, 14;Ru-Mn 14;催化剂上 14;Mn 14;以 14;Mn3O4 14;存在于 14;Ru 14;的表面上. 在加氢过程中, 14;Mn3O4 14;可以与浆液中 14;ZnSO4 14;发生化学反应生成一种难溶性的 14;(Zn(OH)2)3(ZnSO4)(H2O)3 14;盐. 该盐易化学吸附在 14;Ru 14;催化剂表面上, 14;从而在提高 14;Ru 14;催化剂上环己烯选择性起关键作用. 当催化剂中 14;Mn 14;含量为 14;5.4% 14;时, 14;环己烯收率为 14;61.3%, 14;同时具有良好的稳定性和重复使用性能.

Graphical abstractAn Ru-Mn catalyst with an optimum Mn content of 5.4% gave a cyclohexene yield of 61.3%. The chemisorbed [Zn(OH)2]3(ZnSO4)(H2O)3 salt, which was formed by the reaction of Mn3O4 with ZnSO4 in the slurry, improved the selectivity of the Ru catalyst.Figure optionsDownload full-size imageDownload as PowerPoint slide