K+-FeOx/SBA-15催化剂中共存阴离子对其丙烯环氧化性能的影响

考察了在以N2O为氧化剂的丙烯气相环氧化反应中，FeOx／SBA-15催化剂上添加具有不同阴离子的钾盐修饰时，共存阴离子对K^＋-FeOx／SBA-15催化剂的丙烯环氧化反应性能的影响．研究表明，共存阴离子的电子亲和势是影响催化剂活性中心反应性能的重要因素．阴离子的电子亲和势越大，其所修饰的活性氧物种的亲电氧化性高，催化剂的丙烯环氧化性能高．与其它阴离子相比，KCl修饰的FeOx／SBA-15催化剂具有最佳的丙烯环氧化催化性能．

Effect of Counter Anions of Potassium Salts on Propylene Epoxidation Catalyzed by K+-FeOx/SBA-15

The present paper studied the effect of counter anions of potassium salts added in a FeOx/SBA-15 catalyst on the catalytic performances for the epoxidation of propylene with N2O as an oxidant. Although the modification of the FeOx/SBA-15 catalyst with all of the potassium salts investigated in this work could shift the main reaction route from the allylic oxidation to the epoxidation,the nature of the counter anion of potassium exerted a big influence on the catalytic performances, It was found that the electron affinity of the counter anion was a crucial factor in determining the catalytic properties in the epoxidation of propylene with N2O. Catalysts modified by potassium salts with counter anions possessing higher electron affinities exhibited both higher propylene conversion and higher propylene oxide selectivity. The higher catalytic performances probably resulted from the generation of more highly electrophilic oxygen species in the presence of a counter anion possessing higher electron affinity. As compared with other potassium salts such as KF,KBr,KI,KAc and KNO3,the modification of FeOx/SBA-15 with KCl showed the best catalytic performance for the epoxidation of propylene with N2O.