Co^(2+)-NaX催化氧气环氧化苯乙烯的溶剂效应

Effects of Solvents on the Epoxidation of Styrene with Molecular Oxygen Catalyzed by Co^(2+)-NaX

考察了各种具有较低蒸汽压的溶剂(b.p.>100℃)对含钴八面沸石(Co2+-NaX)催化的以氧气为氧化剂的苯乙烯环氧化反应的影响.结果表明,溶剂对环氧化反应具有重要作用,使用酰胺类溶剂如:N,N-二甲基甲酰胺等能够获得优良的催化性能.进一步研究表明,溶剂与分子筛中钴离子的配位作用是苯乙烯发生氧化转化的关键,酰胺类溶剂辅助参与苯乙烯的环氧化反应.使用适当比例的N,N-二甲基甲酰胺和二甲亚砜的混合溶剂能够显著提高苯乙烯的转化率和环氧化物的选择性.

Effects of various solvents with relatively low volatility （b. p. 〉 100 ℃） on the epoxidation of styrene with molecular oxygen using cobalt-containing faujasite （Co^2＋-NaX） as the catalyst have been studied. The results indicate that the solvent can play an important role in the epoxidation of styrene, and superior catalytic performances can be achieved when an acylamide, such as N,N-dimethylformamide （DMF）, is used as the solvent. Farther investigations suggest that the solvent plays a crucial role in the conversion of styrene through coordination to the cobalt ions in molecular sieves, and the acylamide may act as a participator to enhance the epoxidation of styrene with molecular sieves. Both styrene conversion and epoxide selectivity can be obviously improved when a solution of N,N-dimethylformamide （DMF） and dimethyl sulfoxide （DMSO） with an appropriate proportion is used.