硝基芳烃氢化还原反应中高分子负载催化剂的双金属协同效应

制备了聚Ｎ－乙烯基－２－吡咯烷酮ＰＶＰ负载钯催化剂Ｐｄ／ＰＶＰ及各种双金属催化剂（１－ｍ）Ｐｄ－ｍＭ／ＰＶＰ，并用于硝基芳烃的加氢还原中，其中Ｐｄ／ＰＶＰ中加入Ｈ２ＰｔＣｌ６的效果最佳，碱的用量、溶剂和Ｐｄ、Ｐｔ的比例都对催化剂的活性有明显的影响，双金属催化剂０．８０Ｐｄ－０．２０Ｐｔ／ＰＶＰ在温和条件下能高活性，高选择性地催化硝基芳烃还原，得到相应的芳胺。

Bimetallic Synergic Effect of Polymer Supported Catalysts in the Hydrogenation of Nitroaromatics

The catalytic behaviors of poly N vinyl 2 pyrrolidone(PVP) supported palladium monometallic catalyst Pd/PVP and palladium based bimetallic catalysts (1-m)Pd mM/PVP in the hydrogenation of nitroaromatics were studied. The catalyst Pd/PVP shows high catalytic activity and selectivity for the formation of aromatic amines in the hydrogenation of nitrobenzene, m dinitrobenzene etc., but the catalyst shows low activity even no reactivity for other aromatics, for example, the hydrogenation of p nitrobenzoic acid. Among the second metal compounds added, hexachloroplatinic acid is the best one. The effects of the preparative methods, the molar ratio of palladium to platinum, the solvent used and the amount of base on the hydrogenation of nitrobenzene catalyzed by the palladium platinum bimetallic catalysts were investigated. Catalyst 0.80 Pd 0.20 Pt/PVP exhibits the highest catalytic activity in the hydrogenation of nitrobenzene among a series of bimetallic catalysts prepared in alcohol water solution with alternative molar ratios of Pd to Pt. These two metals exhibit obvious synergic effect and the TOF max of the catalyst can amount to 190 min -1 . The catalyst also show high catalytic activity and selectivity for the formation of amines in the hydrogenation of other nitroaromatics, e.g. the TOF max can be up to 216 min -1 in the hydrogenation of m nitrobenzoic acid.