Study on the Structure of Catalitic Acitve Sites by Means of Probe Reaction

为了解决全球范围内的能源短缺和环境污染问题，人们迫切需要开发活性更高、选择性更好的催化剂。为此，有必要阐明控制固体表面催化活性和选择性的因素。由于表面分析技术的显著进步，使确定各种催化剂的表面结构成为可能。因此，我们将质子-氘交换过程的同位素探针反应方法应用于系统改性后的催化剂上，并利用微波波谱技术研究了反应中间体结构与改性后催化剂表面性质的依赖关系，并将该方法应用于ZrO_2上，研究了负载型氧化物催化剂的结构敏感性。TiO_2和ZnO催化剂高度分散在二氧化硅和氧化铝载体上。结果表明，几十个A氧化物颗粒表现出完全不同的催化行为从更大的氧化物颗粒。我们还研究了氧化铝负载的铑羰基簇合物的活性中心结构，发现一个或两个表面铑原子就足以催化该反应。我们还将这种方法应用于更复杂的反应，如氧化，加氢和NO还原与丙烯，并获得有趣的信息，这些反应的选择性的控制因素。

It has been required to develop more active and selective catalysts in these days, to solve the problems on the energy shortage and environmental pollution in the global scale. For this purpose, it is necessary to clarify the factors which control the catalytic activity and selectivity on the solid surface. Because of the remarkable progress on the surface analytic techniques, it is possible to define the surface structures of various catalysts. Accordingly, we applied the isotopic probe reaction method of propene-deuterium exchange process on the catalysts whose surface properties were modified systematically, and investigated the dependencies of the structure of reaction intermediates upon the modified surface properties by means of microwave spectroscopy.We have studied the structure sensitivity of the supported oxide catalysts by applying this method on ZrO_2, TiO_2 and ZnO catalysts highly dispersed on silica and alumina supports. It was demonstrated that several ten A oxide particles exhibit completely different catalytic behavior from larger oxide particles. We also have studied the structure of active sites of alumina supported Rh carbonyl cluster complexes and found that one or two surface Rh atoms are enough to catalyze this reaction. We also applied this method on the more complex reactions like oxidation, hydroformylation and NO reduction with propene and obtained interesting information on the controlling factors of the selectivity of these reactions.