Ni-B/SiO2非晶态催化剂应用于硝基苯液相加氢制苯胺

 考察了Ni－B／SiO2非晶态催化剂在高压液相硝基苯加氢制苯胺反应中的催化活性和选择性．研究表明，该催化剂不仅具有很高的催化活性，而且对苯胺的选择性较高，优于RaneyNi以及其它Ni基催化剂．晶化导致催化剂失活．载体的存在不仅能提高催化剂的分散度，而且能对非晶态结构起稳定化作用；将催化剂保存在乙醇中可保持其活性不变．结合催化剂的表征，讨论了Ni－B／SiO2非晶态催化剂的催化性能与其结构的关系．

Liquid-Phase Hydrogenation of Nitrobenzene to Aniline over Ni-B/SiO2 Amorphous Catalyst

A Ni B/SiO 2 amorphous catalyst, prepared by impregnation of silica support with Ni ions which were reduced by KBH 4 aqueous solution, was employed in liquid phase hydrogenation of nitrobenzene to aniline. In comparison with other Ni based catalysts, such as ultrafine Ni B amorphous alloy, Raney Ni, Ni/SiO 2, and the crystalline Ni B/SiO 2, the as prepared Ni B/SiO 2 amorphous catalyst exhibited higher activity and better selectivity for aniline. The catalyst could be kept in ethanol without significant decrease in the activity for a long period. However, deactivation of the catalyst was observed when it was crystallized at high temperature. The relationship between the catalytic activity and the nature of the active sites was discussed based on various characterizations including BET, SEM, XRD, XPS, hydrogen chemisorption, etc . The higher activity of the Ni B/SiO 2 amorphous catalyst could be attributed to the higher dispersion of the Ni active sites and was closely related to both the structural and electronic effects on the catalytic property of the Ni active sites. The promoting effect of the silica support was interpreted in terms of its dispersing effect which increased the surface active area of the catalyst on one hand and inhibited the crystallization of Ni B amorphous alloy on the other.