Tantalum-based Photoresponsable Material Supported Cobalt Catalyst In Photothermal Fischer-tropsch Synthesis Reaction And Reaction Mechanism Research

The Fischer-Tropsch synthesis?FTS?reaction is a process which converts syngas?CO/H₂?into long-chain hydrocarbons under appropriate conditions by catalyst.The FTS reaction generally follows the ASF distribution,which limits its development in a certain sense.In this thesis,the light conditions were introduced on the basis of FTS reaction condition,and the reaction was synergistically catalyzed by light and heat.The catalytic mechanism was explored in order to find new path to break the limitation of ASF distribution.The main contents and results are summarized as follows:?1?Two kinds of photoresponsive supports,TaON and Ta₃N₅,were prepared.The experimental conditions for high-efficiency,large-scale and simple preparations of high-purity compounds have been determined.Characterizations by XRD,XPS,SEM and other techniques indicated that both compounds are pure phases.The study for their stability,light response performance and related structure showed that they can be used as photothermal FTS light-sensitive supports.?2?Impregnation method for active component has been explored.The catalysts were prepared by using an entirely new liquid phase reduction method.The photothermal FTS catalysts with ultra-small and highly dispersed active component were obtained.Compared with that of the catalyst prepared by traditional impregnation method,the catalytic activities of the new catalysts are greatly improved.?3?The 15%Co-TaON-H catalyst prepared by the new impregnation method has excellent performance under UV light and heat conditions.The CO conversion is two times of the catalyst prepared by traditional impregnation method under the same C₅₊selectivity.For Ta₃N₅-based catalysts,in order to improve the poor product selectivity under high CO conversion,molecular sieves were used.It was found that the molecular sieve introduced in the photothermal FTS system has a regulating effect on the distribution of the product,which paves the way for subsequent studies.?4?The reaction mechanism of the photoelectrons and holes in photothermal FTS has been further studied.The mechanism of effects of the photogenerated electrons and holes on the distribution of photothermal FTS reaction products is proposed.It provides theoretical references for the future design of new photothermal FTS catalytic system.