负载型MgO催化苯乙酮Meerwein-Ponndorf-Verley反应中的载体效应  

Support Effect on the Meerwein-Ponndorf-Verley Reduction of Acetophenone over Supported Magnesium Oxide Catalysts

作　　者：徐春雷[1] 张波[1] 袁剑[1] 卢晗锋[1] 陈银飞[1] 葛忠华[1] 

机构地区：[1]浙江工业大学化学工程与材料学院工业催化研究所,杭州310014

出　　处：《化学学报》2011年第4期368-374,共7页Acta Chimica Sinica

摘　　要：通过浸渍法制备活性炭(AC)、全硅介孔分子筛MCM-41、硅胶(SiO2)、γ-Al2O3等四种载体负载的MgO催化剂,考察其在以异丙醇为氢源的苯乙酮Meerwein-Ponndorf-Verley(MPV)反应中的催化活性,并和纯MgO进行对比研究,同时对样品进行XRD、TEM、N2吸附-脱附、XPS及CO2-TPD等表征分析,研究载体效应对催化剂活性的影响.结果表明:纯MgO因其比表面积较小,表面暴露的碱中心数目较少,其活性较低.10%MgO/AC中MgO具有良好的分散性,且与AC载体不发生强相互作用,MgO以小晶粒形式存在于载体表面,致使催化剂表面的碱中心数目显著提高;另外,苯乙酮上苯环π电子与AC载体中石墨层π电子可能存在相互作用,致使催化剂活性中心附近的苯乙酮浓度增大;上述两方面原因使该催化剂具有良好的活性.而在10%MgO/MCM-41,10%MgO/SiO2,10%MgO/γ-Al2O3中,载体均与MgO发生强相互作用,使得其碱中心数目急剧下降,导致其催化活性不明显.Magnesium oxide supported on active carbon （AC）, siliceous mesoporous molecular sieve MCM-41, silica （SiO2） and γ-Al2O3, respectively, was prepared by the impregnation method. Their catalytic activities in the Meerwein-Ponndorf-Verley （MPV） reduction of acetophenone with 2-propanol as a reducer were investigated, and campared to that of pure MgO catalyst. At the same time, the catalysts were characterized with XRD, TEM, N2 adsorption-desorption, XPS and CO2-TPD methods. Support effect on the activity of catalyst was studied. The results show that the catalytic activity of pure MgO is low, due to the smaller specific surface area resulting in the less basic sites on its surface. In the 10% MgO/AC catalyst, the high surface area of AC and no strong interaction of MgO with AC support favor the high dispersion of MgO on the surface of AC to form very small crystallites leading to a clear increase of basic sites on the surface of catalyst. On the other hand, the concentration of acetophenone near the active sites in the catalyst increases because of the possible n-electron interaction between the benzene ring in the acetophenone and graphite layer of AC support. The effects of above two aspects lead to a significant increase of the catalytic activity of 10% MgO/AC campared to pure MgO. The 10% MgO/MCM-41, 10% MgO/SiO2, 10% MgO/γ-Al2O3 are hardly active due to the strong interaction of MgO with the support materials resulting in the dramatic decrease of number of basic sites on the surface of these catalysts.

关 键 词：载体效应 氧化镁 苯乙酮 MPV反应 

分 类 号：TQ244.2[化学工程—有机化工]