Mn(salen)/Al-MCM-41催化剂的制备及其对苯乙烯环氧化反应的催化性能

Preparation of Mn(salen)/Al-MCM-41 Catalyst under Microwave Irradiation and Its Catalytic Performance in Epoxidation of Styrene

报道了一种用微波固相法制备Mn(salen) /Al MCM 4 1催化剂的新方法 ,并与常规制备方法进行了比较 .FT IR表征结果表明 ,微波固相方法和常规方法均能成功地将Mn(salen)配合物固载于Al MCM 4 1介孔分子筛上 ,且微波固相法制备的Mn(salen) /Al MCM 4 1催化剂在 1 4 4 8cm-1 处具有更强的吸收带 .比较了不同方法制备的催化剂在苯乙烯环氧化反应中的催化性能 ,发现微波固相法制备的Mn(salen) /Al MCM 4 1催化剂具有较高的催化活性和环氧化物选择性 .此外 ,催化剂的性能与制备过程中微波辐射的时间有关 .考察了反应时间和反应温度对微波固相法制备的催化剂性能的影响规律 ,随着反应时间的延长和反应温度的升高 。

Mn(salen) complex used as a catalyst in the epoxidation of unfunctional alkene for synthesis of intermediates of pharmaceuticals and agrochemicals has attracted public interest. Three methods for immobilization of Mn(salen) complex on Al MCM 41 molecular sieve were adopted: (1) the sample prepared by traditional ion exchange in solution is denoted as Mn(salen)/Al MCM 41(IE); (2) the sample prepared by impregnating the mixture of salen ligand, (CH 3COO) 2Mn, LiCl and Al MCM 41 with dichloromethane and evaporating automatically, and then irradiated by microwave, is denoted as Mn(salen)/Al MCM 41(IP MW); (3) the sample prepared by solid state interaction between Mn(salen) complex and Al MCM 41 under microwave irradiation is denoted as Mn(salen)/Al MCM 41(MW). Mn(salen) complex of the three samples was evidently immobilized on Al MCM 41 from the major IR bands in the range of 1?200 ～ 1?800 cm -1 . However, the relative intensity of the bands at 1?295 and 1?448 cm -1 depended on the preparation methods. The catalytic performance of the three catalyst samples in the epoxidation of styrene was investigated. It was found that the catalyst sample Mn (salen)/Al MCM 41(IP MW) exhibited the highest activity and selectivity for phenyloxirane. With increasing reaction time and temperature, the selectivity for phenyloxirane decreased. The reuse of Mn(salen)/Al MCM 41(IP MW) showed no leaching of salen ligand from Mn(salen)/Al MCM 41.