Design And Preparation Of Cu-based Nanocatalyst With Dual Photothermal Response And Performance Study On CO₂ Hydrogenation Synthesis Fuel

Heterogeneous CO₂ hydrogenation catalytic reaction,as a strategy of net CO₂emission reduction and green carbon resource recycling,plays an important role in alleviating global warming and energy shortage.However,most of the research on the CO₂ hydrogenation synthesis reaction has focused on thermal catalysis,this kind of reaction consumes a lot of energy and therefore induces additional CO₂ emissions,which greatly limits its development in industry.Regarding the issue above,this paper proposes a method of coupling thermocatalysis and photocatalysis technology,and designs a series of Cu-based catalysts with photothermal response for thermal/photothermal catalytic CO₂ hydrogenation,and the relationship between the physical and chemical properties,catalytic activity,and photothermal catalytic mechanism of the catalyst was also discussed.The results are as follows:?1?By using hydrotalcite?CuCoAl-LDH?as a precursor,a Cu-Co alloy supported catalysts which were highly dispersed on the carrier Al₂O₃ were obtained through hydrogen reduction.The catalytic performance of methane production via CO₂ hydrogenation was investigated under thermal and photothermal conditions.The results demonstrate that the photothermal synergistic catalysis shows a better performance of CO₂ hydrogenation to methane than the single thermal catalysis.Under atmospheric pressure?0.1Mpa?and low temperature?280??reaction conditions,the CO₂ conversion rate is 41.0%,and the methane selectivity is as high as 96.6%.?2?Two catalysts with different ratios of Cu/ZnMgO?4-3-3?and Cu/ZnMgO?3-2-5?were prepared by hydrothermal synthesis method.This composite material contains metal Cu with surface plasmon resonance?SPR?effect and n-type semiconductor ZnMgO?solid solution?,these components could generate Schottky junction which increases the lifetime of hot electrons generated by the SPR effect of Cu.The catalytic activity of the catalyst to synthesize methanol by CO₂hydrogenation under thermal and photothermal conditions was also investigated.The results show that compared with Cu/ZnMgO?4-3-3?catalyst,Cu/ZnMgO?3-2-5?catalyst has better performance in the photothermal co-catalysis of CO₂hydrogenation to methanol.Under the reaction conditions of temperature 180?and pressure 2.5Mpa,the CO₂ conversion rate is 16.1%,and the selectivity of methanol is as high as 87.0%.Using it as a model catalyst,the catalytic mechanism of photothermal co-catalysis of CO₂ hydrogenation to methanol was explored in detail.?3?The sol-gel method was used to prepare Cu/CuFe₂O₄ catalyst,and the catalytic performance in thermal and photothermal catalytic CO₂ hydrogenation reactions was investigated.The results show that at a temperature of 240?and a reaction pressure of 2.5 MPa,the CO₂ conversion rate is 33.2%and the hydrocarbon selectivity is 98.0%for the photothermal catalytic reaction.Among them,the selectivity ratio of methane and light alkanes?C₂-C₄?in hydrocarbons is close to 1:1.From the PXRD of the catalyst after the reaction,it was found that the phase of catalyst had been reconstructed,and a new phase Cu/FeCO₃ was generated.