Catalytic Performance Of CuCo-based Catalysts For Mixed Alcohols Synthesis From CO₂ Hydrogenation

Recently,global warming is one of the chief environmental issues human is facing,while CO₂ concentration is the crucial issue in causing global climate change.The CO₂ hydrogenation reaction is a promising research for the production of chemicals and fuels.It can not only reduce CO₂ emissions but also supply for the insufficiency of fossil fuels.Since CuCo-based catalysts exhibit good performance for higher alcohols synthesis?HAS?under mild reaction conditions,this thesis prepared a series of Cu Co bimetallic catalysts by different preparation methods to tailor the surface structure of active nanoparticles.The relationship of catalyst structure and CO₂hydrogenation performance was explored.The results are summarized as follows:?1?CuCo bimetallic catalysts with Cu/Co=1/2 under different NaOH titration concentrations were prepared by conventional co-precipitation method and their CO₂hydrogenation performances were evaluated.It was found that although the two catalysts obtained have the same active components,the catalytic performance is quite different because of the different degree of NaOH concentration.When the NaOH concentration is 1 mol/L,methanol selectivity is 45.9%and methane selectivity is52.9%over CuCo-r-1 catalyst at 210?.When the NaOH concentration is 0.1 mol/L,methanol selectivity is 21.3%and methane selectivity is 77.0%over CuCo-r-0.1catalyst at 210?.So we can tailor the distribution of the products by regulating microstructure of the surface of bimetallic catalysts which was controlled by different concentration of alkali.?2?Highly ordered mesoporous copper-cobalt composite oxides were prepared using KIT-6 as template by the nanocasting method with various Cu and Co ratios.The catalytic performance of CO₂ hydrogenation to higher alcohols was investigated.It was found at 220?,Cu/Co=1/2,CO₂ conversion was 13.1%,the selectivity for total alcohols and C₂₊OH was 49.8%and 98.5%,respectively,and the space-time yield?STY?was as high as 44.4 mg/mL/h.Among the products,ethanol and isopropanol in C₂₊OH were predominant.?3?The Cu Co₂S₄ catalyst was prepared by hydrothermal method and its CO₂catalytic conversion performance was explored.It was found CuCo₂S₄ showed no catalytic activity.After reducing with hydrogen at 380?,there was still no activity.It was found that the main phase was changed to Co₃₆S₃₂2 and CuS₂ after CO₂hydrogenation.The reason may be that the S species produced poisoned the catalyst during the reaction.