丙烯环氧化制环氧丙烷是催化领域的最关键的挑战之一.本文对作者等近年来开展的以一氧化二氮为氧化剂的铁催化体系和以氧气为氧化剂的铜催化体系的研究进展进行了综述.在这两类催化体系中,碱金属离子(特别是K+)的修饰作用均是获得较高环氧丙烷选择性的关键.碱金属离子通过调变催化剂中铁或铜物种的分散度、配位环境和酸碱性等,实现了对反应途径的调控,使反应朝着有利于环氧丙烷生成的方向进行.活性金属组分(铁或铜)与氧化剂(一氧化二氮或氧气)间的特定的组合对丙烯环氧化反应的发生也起着重要作用.推测在两类催化体系中,氧化剂均在具有特定结构和价态的铁或铜活性位上活化,产生导致丙烯环氧化反应发生的亲电性活性氧物种.The epoxidation of propylene to propylene oxide is one of the most challenging research targets in catalysis.This review highlights our recent studies on the epoxidation of propylene by nitrous oxide and oxygen catalyzed by iron-and copper-based heterogeneous catalysts.For both iron-and copper-based catalysts,the modification with an alkali metal ion(especially K+) plays pivotal roles in obtaining high selectivity to propylene oxide.Alkali metal ions may enhance the dispersion of iron and copper species,change their coordination environments,and regulate the surface acid and base properties,and thus contribute to the selective formation of propylene oxide.The unique combination of active metal component(iron or copper) and oxidant(nitrous oxide or oxygen) is also crucial for the epoxidation of propylene.We propose that the oxidant is activated on active iron or copper sites with peculiar structures and oxidation states,forming active oxygen species responsible for the epoxidation of propylene.国家自然科学基金(20625310,20773099,20433030);; 国家重点基础研究发展计划(973计划,2003CB615803,2005CB221408
