钯、铂催化剂在硝基苯催化加氢合成对氨基苯酚反应中的比较

Comparison with catalytic properties of palladium and platinum catalysts for liquid catalytic hydrogenation of nitrobenzene to p-aminophenol

制备了一系列不同金属粒径的活性炭负载钯、铂催化剂,用于硝基苯液相催化加氢合成对氨基苯酚反应。采用N_2-物理吸附、联碱滴定和TEM等表征手段对活性炭载体及其负载钯、铂催化剂进行表征。结果表明,对氨基苯酚选择性与钯、铂活性组分的金属粒径存在紧密的内在联系,说明活性炭负载钯、铂催化剂对于硝基苯液相催化加氢合成对氨基苯酚的反应均为结构敏感反应。同时,金属粒径小的钯和铂活性组分对羟基苯胺中间体的吸附较弱,对氨基苯酚选择性高;铂活性组分对羟基苯胺中间体的吸附较钯弱。

A series of activated carbon supported palladium and platinum catalysts with different metal particle sizes were prepared for liquid phase catalytic hydrogenation of nitrobenzene to p-aminophenol. The activated carbon carrier and the as-prepared catalysts were characterized by N2-adsorption, associated base titration and TEM methods. The results showed that the selectivity to p-aminophenol and the metal particle size of palladium and platinum active component had close inherent relation, indicating that the synthesisof p-aminophenol from the liquid phase catalytic hydrogenation of nitrobenzene over the active carbon sup- ported palladium and platinum catalysts was a structure sensitive reaction. Meanwhile, the adsorption capacity of hydroxy aniline intermediate on active components with the small particle size were weaker, and the adsorption capacity of hydroxy aniline intermediate on platinum active component was weaker than that on palladium active component ,which were conducive to the improvement of selectivity to p-aminophenol.