摘要
本文应用程序升温脱附技术(TPD),以乙酸作为分子探针,考察了无铬Fe—K系混合氧化物乙苯脱氢催化剂的表面碱性。Fe—K系催化剂表面至少存在两种强度不同的碱中心,其中强碱中心b态对乙苯催化脱氢贡献较大;而催化剂表面同时具有适当的碱强度和密度是获得较好催化性能的重要条件。研究结果还发现,乙苯脱氢反应可能类似于强碱催化的双分子消除E2反应,其中催化剂表面碱位起着类似于E2历程中强碱试剂的作用。
The surface basicity of non-chromic Fe-K mixed oxide catalysts for dehydrogen-ation of ethylbenzene has been studied by using Temperature-Programed-Desorption (TPD) method with acetic acide as molecular probe. There arc at least two kinds of basic centers on catalyst surface, of which the stronger 'b' basic centers have greater contribution to dehydrogenation of ethylbenzene than the weaker 'a' basic centers. It is necessary that moderate strength and density of base exist on catalyst surface for high catalytic activity. The study also shows that the dehydrogenation kinetic mechanism of ethylbenzene on Fe-K mixed oxide catalsts may be similar to that of the dimolecular elimination reaction (E2), and the surface basic center 'b' acts as the strong base in E2 mechanism.
