本项目拟在水热稳定性和耐酸性都相对较好的氧化硅介孔材料孔道限域空间中涂覆氧化铝层，制备介孔氧化硅-氧化铝复合材料，并负载铂纳米粒子，制备铂/氧化铝/氧化硅介孔材料催化剂。这样不仅可以保留氧化铝负载铂催化剂的优良性能，还可以引入氧化硅介孔材料的孔道限域效应，同时也可以通过制备方法的调变提高氧化铝负载铂催化剂的耐酸性。铂/氧化铝/氧化硅介孔材料催化剂经过手性修饰后用于丙酮酸乙酯和2-氧-4-苯基丁酸乙酯的不对称氢化反应或直接用于肉桂醛选择加氢反应。将详细考察限域空间中铝配位状态对铂纳米粒子电子状态的影响、探明主客体氧化物相互作用及其对铂纳米粒子电子状态的影响机制、研究氧化硅介孔材料孔道尺寸及孔道对称性对负载铂纳米粒子上醛酮化合物加氢反应性能的影响，提出限域空间中铂纳米粒子表面醛酮化合物吸附、活化和加氢反应机理。申请者近年来开展了相关前期工作，研究积累为项目顺利完成打下了扎实的基础。

Pt catalysts are active for liquid-phase hydrogenation of carbonyl compounds, especially for asymmetric hydrogenation of alfa-functionalized ketones after chirally modified with cinchona alkaloids. Higher than 90% ee value can be achieved for the asymmetric hydrogenation of pyruvate esters on chirally modified Pt/alumina catalyst in acetic acid. For the enantioselective hydrogenation of ethyl 2-oxo-4-phenylbutyrate (EOPB), of which the hydrogenated product is the intermediate for synthesis of ACE inhibitors, about 80% ee value could be obtained with chirally modified Pt/alumina catalyst under optimal conditions such as in acetic acid. However, traditional Pt/alumina catalysts will be easily peptized under the acidic conditions, resulting in poor reusablity of Pt/alumina catalyst for the asymmetric hydrogentation of alfa-functionalized carbonyl compounds in acetic acid..In addition, enormous attention has been paid to confinement effect of mesopores on catalysis. The activity or selectivity may be changed via the confinement effect. In this project we will introduce highly-dispersed amorphous alumina into confined mesopores of ordered mesoporous silicas such as SBA-15, KIT-6 and SBA-16, which have relatively high hydrothermal ability and are quite stable under acidic conditions, to prepare mesoporous silica-alumina composites. The stability of alumina composites will be increased by modulating preparation parameters. Furthermore, the mesopore confinement effect might affect the catalytic performance. .Pt nanoparticles will be supported on the mesoporous silica-alumina composites to prepare Pt/alumina/mesoporous silica catalysts for the chiral hydrogenation of ethyl pyruvate and EOPB after chirally modified with cinchona alkaloids. Then to broaden the substrate scope, selective hydrogenation of a typical alfa,beta-unsaturated aldehyde, such as cinnamaldehyde, will be carried out. The effect of coordination state of Al species (four-coordinated, five coordinated or six-coordinated), the host-guest interaction, the electronic state of Pt nanoparticles and the mesopore size (4.6-30 nm of SBA-15) or symmetry (P6mm symmetry of SBA-15, Ia3d symmetry of KIT-6 or Im3m symmetry of SBA-16) on the target reactions will be investigated in detail. Moreover, based on the catalytic performance and the characterization results including 27Al NMR, IR spectra of pyridine and CO adsorption, XPS, EXAFS etc., the host-guest interaction and its effect on the electronic state of Pt nanoparticles will be studied as well. In combination with the IR results of reactant adsorption, the TPD results of intermeidate or product desorption and the relevant TPSR information about the reaction intermediates, the mechamisms about adsorption, activation and hydrogenation of carbonyl compounds on the Pt nanoparticles confined inside the mesopores will be proposed.