Ni-Co-B非晶态合金催化肉桂醛常压加氢制3-苯丙醛的研究

采用化学还原法制备了一系列Ni-Co-B非晶态合金催化剂, 通过调变金属盐混和液中Ni^2＋/Co^2＋的比例, 可制得不同Co含量的Ni-Co-B非晶态合金. 用ICP, BET, XRD, TEM, SAED, DSC, XPS和H₂-TPD对其组成、结构、粒子大小、表面形貌和表面电子态进行了系列表征, 并以肉桂醛常压加氢制苯丙醛作为探针反应, 考察了所制备的Ni-Co-B非晶态合金的催化性能. 结果表明, Ni-Co-B非晶态合金中Ni为活性中心, Co的引入可显著增加其催化活性. 由于催化测试中金属总量固定为1.0 g, 因此增加Ni-Co-B中Co的含量具有正负两方面的效应. 一方面, 由于Ni活性位数目的减少加氢活性降低; 另一方面, Co对Ni活性中心具有协同作用, 有利于增加合金的无序度、金属-类金属间相互作用、表面Ni含量和电子相互作用, 从而提高催化活性. 最佳Co与(Ni＋Co)摩尔比含量的范围为0.2～0.5.

Study on Cinnamaldehyde Hydrogenation to 3-Phenylpropyl Aldehyde at Atmospheric Pressure over Ni-Co-B Amorphous Alloys

A series of Ni-Co-B amorphous alloy catalysts have been prepared by chemical reduction and their Co contents could be adjusted via changing Ni^2＋/Co^2＋ in reaction mixture. According to various characterizations, such as ICP, BET, XRD, TEM, SAED, DSC, XPS and H₂-TPD, the effect of cobalt content on the structural and electronic characteristics of Ni-Co-B catalyst was studied briefly. Meanwhile, their catalytic activities were evaluated by using liquid phase hydrogenation of cinnamaldehyde to 3-phenylpropyl aldehyde at atmospheric pressure as a probe. Results showed that the active center in the ternary alloy was Ni, whose catalytic activity could be greatly enhanced by introducing Co. Taking into account that the total amount of metal was fixed at 1.0 g in each run of the activity test, increasing Co content in Ni-Co-B alloy has positive effect and negative effect on its catalytic activity. On one hand, the catalytic activity will reduce due to the decreasing of the number of Ni active center. On the other hand, the synergetic effect of cobalt on Ni active center favors increasing the structural disorder of Ni-Co-B sample, the interaction between metal and metalloid, the surface Ni content and the electron interaction, which, in turn, enhances the catalytic activity. Suitable molar ratio of Co to (Ni＋Co) was found as 0.2～0.5.