Development of Nobel Catalytic Process Aimed at Green Chemistry by Functionalization of Solid Surface

该研究表明，高功能化多相催化剂的设计有助于开发环境可接受的化学过程，如利用分子氧和过氧化氢选择性氧化碳氢化合物、二氧化碳固定和C-C键形成反应。结果总结如下。选择性氧化：为了制备高性能的氧化催化剂，我们广泛地利用了晶体金属氢氧化物的独特性质，如水滑石和羟基磷灰石，以及金属团簇。基于阳离子交换能力，钌阳离子可以作为单体固定在水滑石的水镁石层中。通过Ru和Co离子之间的氧化还原相互作用，在水镁石层中引入Co离子，大大增强了氧化催化作用。这些功能化材料能有效地催化各种醇类和芳烃的氧化生成相应的羰基化合物。通过简单的离子交换过程，在羟基磷灰石表面也产生了分离的钌，作为醇和胺的有氧氧化的有效多相催化剂。提出了一种与钌离子单体结构有关的诺贝尔氧化机理。还发现水滑石的碱基在过氧化氢作为氧化剂的情况下促进烯烃和吡啶的单氧化反应。此外，我们还开发了在分子氧存在下作为芳烃乙酰氧化高活性催化剂的巨大钯簇的制备方法。上述钯簇的突出催化作用归因于其表面由金属钯和邻近钯阳离子组成的特定系综位。水滑石煅烧制备的镁铝混合氧化物表面具有酸碱双官能团性质，在温和的反应条件下具有独特的催化作用，可将二氧化碳与各种环氧化物环加成。在XAFS测量的基础上，讨论了镁铝混合氧化物表面酸碱位的产生。(3) C-C键形成反应：钛离子交换蒙脱土作为强固体酸催化剂，与羰基化合物进行芳香烷基化反应，合成有价值的特种聚合物原料。我们发现水滑石催化各种醛缩合成相应的醛醇化合物。上述固体催化剂易于从反应混合物中分离，且可循环利用，具有较高的活性和选择性。少

This research demonstrated that the design of highly-functionalized heterogeneous catalysts contributes to developing environmentally-acceptable chemical processes such as selective oxidations of hydrocarbons using molecular oxygen and hydrogen peroxide, fixation of carbon dioxide, and C-C bond formation reactions. The results are summarized as below.Selective OxidationsFor preparation of high performance oxidation catalysts, we extensively utilized unique characters of crystalline metal hydroxides, i.e, hydrotalcite and hydroxyapatite, and metal clusters.Ruthenium cation could be immobilized in the Brucite layer of the hydrotalcite as monomeric species based on the cation-exchange ability. The oxidation catalysis was greatly enhanced by introducing Co cation in the Brucite layer through Redox interactions between Ru and Co cations. These functionalized materials efficiently catalyzed oxidations of various alcohols and aromatic hydrocarbons to the corresponding carbonyl compounds in th … More e presence of molecular oxygen.The isolated Ru species are also created on the surface of hydroxyapatite by a simple ion-exchange procedure, which acted as an effective heterogeneous catalyst for aerobic oxidation of alcohols and amines. A nobel oxidation mechanism was proposed in relation to the monomeric structure of the Ru cations.It was also found that base sites of hydrotalcites promotes monooxygenation type reactions of olefins and pyridines using hydrogen peroxide as an oxidant.Further, we developed preparation method of the giant palladium cluster as a highly active catalyst for the acetoxylation of aromatic hydrocarbons in the presence of molecular oxygen. The prominent catalysis of the above Pd cluster is ascribed to specific ensemble sites composed of metallic Pd and neighboring Pd cations on its surface.Fixation of Carbon DioxideThe surface of Mg-Al mixed oxides obtained by calcination of hydrotalcites showed acid-base bifunctional properties and unique catalysis for the cycloaddition of carbon dioxide to various epoxides under mild reaction conditions. The generation of acid-base sites on the surface of the Mg-Al mixed oxide was discussed on the basis of XAFS measurements.(iii) C-C Bond Formation ReactionsTitanium cation-exchanged montmorillonite acted as a strong solid acid catalyst for aromatic alkylations with carbonyl compounds to synthesize valuable raw materials for speciality polymers. We found hydrotalcite-catalyzed the condensation of various aldehydes to the corresponding aldol compounds.The above solid catalysts were easily separated from the reaction mixture and recyclable keeping their high activities and selectivities. Less