骨架型Ni—P非晶态合金的制备及其在苯加氢中催化性能的研究

采用骤冷法制备Ni-Al-P非晶态合金，通过碱抽滤得到骨架型Ni-PD催化剂（Raney Ni-P），其非晶态结构由XRD和EXAFS证实。选择工业上具有重要应用价值的苯饱和加氢反应为探针，测定了上述催化剂的催化活性（包括吸氢速率、转化率和TOF值）和对环己烷的选择性，并与其对应的由传统骤冷法制备的Ni-PD非晶态合金、晶化Paney Ni-P以及工业上常用的Raney Ni催化剂进行了比较。实验结果显示，Raney Ni-P的催化性能显著优于其他三种催化剂，而且DSC分析显示了具有较好的热稳定性，因此具有良好的工业化应用前景。通过考察苯浓度、H2压力和反应温度对加以应速率的影响，确定了在Raney Ni-P催化剂上苯加氢反应的动力学速率方程和表现活化能，并提出了可能的反应机理。通过ICP，XRD，XPS，EXAFS，TEM，BET，氢吸附等一系列表征，讨论了催化剂的活性中心结构特征与其催化活性的关系。Raney Ni的催化活性高于传统Ni-P主要归因于其比表面积（分散度）,而Raney Ni-P的催化活性高于Raney Ni主要归因于催化活性中中心本质的区别。由于非晶态合金Ni-P中无显著的电子转移，因此几何效应起主要的促进作用。Raney Ni-P的晶化失活则同时归于分散度和活性中心结构的改变。

Preparation of skeletal Ni-P amorphous alloy and the study of its catalytic properties during benzene hydrogenation

The skeletal Ni P amorphous alloy(Raney Ni P) was prepared by alkali leaching a Ni P Al amorphous alloy obtained by the rapid quenching technique. Its amorphous structure was confirmed by both the XRD and EXAFS. By using liquid phase benzene hydrogenation, an important reaction in industrial production, the selectivity to cyclohexane and the catalytic activity(including hydrogen uptake rate, reaction conversion and TOF value) of the as prepared Raney Ni P catalyst were measured. In comparison with the corresponding Ni P amorphous alloy obtained via the traditional rapid quenching technique, the crystallized Raney Ni P, and Raney Ni which was widely used in industry, the Raney Ni P catalyst exhibited much higher activity besides the perfect selectivity to cyclohexane. The DSC analysis also revealed its high thermal stability. These results demonstrated its potential application in industrial processes. By measuring the effects of the benzene concentration, the hydrogen pressure, and the reaction temperature on the hydrogenation rate, the reaction kinetics and the apparent activation energies were determined, based on which, a plausible mechanism was proposed. The higher activity of Raney Ni P than that of traditional Ni P was mainly due to its higher surface area. While the higher activity of Raney Ni P than that of Raney Ni was mainly attributed to the nature of the active sites. Since no significant electronic interaction between Ni and P in Ni P amorphous alloy was found by XPS spectra, the geometric effect was considered as the main promoting effect, which was briefly discussed according to various characterizations, such as ICP, XRD, EXAFS, BET, and hydrogen chemisorption. The crystallization deactivation of Raney Ni P amorphous alloy was attributed to the change in both the surface area and the structure of the active sites.