准均相的银纳米催化剂用于高选择性催化还原芳香硝基化合物

Quasi-Homogeneous Silver Nanocatalysts for Highly Selective Catalytic Reduction of Nitroaromatic Compounds

摘要:

银纳米催化剂作为硝基还原催化剂具有活性高、成本低、合成简单的优势。以聚酰胺酸盐为稳定剂，在水相中以硼氢化钠为还原剂、原位制备了聚酰胺酸盐负载的银纳米粒子(AgNPs-PAAS)。表征显示AgNPs的平均粒径为7.8 nm，在PAAS的稳定作用下，AgNPs在水相中呈“准均相”分散。常温、纯水相条件下，以硼氢化钠为还原剂，研究了AgNPs-PAAS催化剂对芳香硝基化合物的还原反应的催化性能。结果表明，AgNPs-PAAS催化剂对芳香硝基化合物的还原反应具有较高的催化活性，且能耐受一些底物的敏感基团(对位卤素原子和羰基)。基于聚酰胺酸盐的pH敏感性，AgNPs-PAAS催化剂可通过调整溶液pH值实现回收再利用，在重复催化3次后仍保持初始活性。

Abstract:

As nitro reduction catalysts， silver nanocatalysts have the advantages of high activity， low cost and simple synthesis. Poly（amic acid） salt-supported silver nanoparticles （AgNPs-PAAS） were prepared in situ with poly（amic acid） salt as a stabilizer and sodium borohydride as a reducing agent in aqueous solution. The average particle size of AgNPs is 7.8 nm， and AgNPs are dispersed quasi-homogeneously in water under the stabilization of poly（amic acid） salt. The catalytic performance of AgNPs-PAAS catalyst for the reduction of aromatic nitro compounds was studied at room temperature and in pure water， with sodium borohydride as a reducing agent. The results show that AgNPs-PAAS catalyst has high catalytic activity for the reduction of aromatic nitro compounds， and can tolerate some sensitive groups of substrates （para-halogen atoms and the carbonyl group）. Due to the pH sensitivity of poly（amic acid） salt， AgNPs-PAAS catalyst can be recovered and reused by adjusting the pH value of solution， and the initial activity of AgNPs-PAAS catalyst can still be maintained after three repetitions of catalysis.