Synthesis And Catalytic Performance Of Photo-response Carrier Supported Iron-based And Cobalt-based Catalysts For Photothermal Synergetic Driven Fischer-tropsch Synthesis

Fischer-Tropsch synthesis?FTS?converts carbon monoxide and hydrogen to clean liquid fuels under the suitable conditions and the existence of catalysts,giving priority to long-chain hydrocarbons and providing a most efficient solution against the increasing energy crisis.Photothermal Fischer-Tropsch synthesis is the synthesis that studies the catalytic performance of Fischer-Tropsch synthesis by introducing light on the basis of traditional thermal catalysis.Photothermal Fischer-Tropsch synthesis may provide a new solution to break the traditional ASF distribution and is significant in utilization of energy cleanly and efficiently.In this thesis,a series of bifunctional catalysts were designed and synthesized by choosing photo-response supports such as SiC,CoAl₂O₄,and thermos active components such as cobalt and iron,and their catalytic performance in different catalytic conditions were studied.The results are summarized as follows:?1?The 15%Co/SiC catalyst was prepared,using using visible light response non-metallic semiconductor SiC as support,and its catalytic performance under thermal and photothermal conditions was studied.It was found that light illumination could improve CO conversion,the alkane to olefin ratio?S=/S°?and C₅₊ selectivity,but decrease CH₄ selectivity.The results suggest that the introduction of light source was conductive for the conversion of CO and chain growth,which was different from the non-photo active support SiO₂.?2?The 15%Co/CoAl₂O₄ and 15%Co/CoAl₂O₄-Al₂O₃ catalysts were prepared by modulating the ratio of Co/Al.The thermal and photothermal catalytic performance were studied respectively.It was found that the product distribution rule of these two kinds of catalysts was similar.Compared with the thermal catalysis,the photothermal catalysis could improve CO conversion,C₅₊ selectivity and S-/S° ratio obviously,and decrease CH₄ selectivity,which illustrates that the introduction of light source is beneficial to the conversion of CO and the reduction of Co.Furthermore,compared to 15%Co/CoAl₂O₄ catalyst,the 15%Co/CoAl₂O₄-Al₂O₃ catalyst showed enhanced catalytic performance,which was attributed to the formation of heterojunction between CoAl₂O₄ and Al₂O₃.Meanwhile,the 15%Co/CoAl₂O₄-Al₂O₃ was tested for photothermal catalysis under different light source.It was found that the catalytic activity was the highest under irradiation of visible light.?3?By using Fe as the thermal active component,the 15%Fe/SiC catalyst was prepared,and its catalytic performance was evaluated under different catalytic conditions.The as-prepared catalyst showed improved catalytic activity under photothermal condition.It was found that light illumination could improve CO conversion?C₅₊ selectivity and S=/S° ratio,but decrease CO₂ selectivity,which was comparable to our earlier exploration.The in-situ produced carbon nanofiber was beneficial to the catalytic reaction.