Promotional Effect Of Surface-interface Active Sites On The Zr-Ce Oxide Solid Solution Surrounded Cu-based Catalyst With Inverse Structure In CO₂ Hydrogenation

In recent years,the excess consumption of fossil fuels has caused huge emission of greenhouse CO2 gas,which leads to more and more serious environmental changes.Therefore,the effective conversion of CO2 into highvalue chemicals(e.g.,methane,methanol,and olefins)is a promising topic.Among them,the direct CO2 hydrogenation to produce methanol using hydrogen obtained through clean and renewable energy sources(e.g.,solar energy,hydropower,wind power,or biomass)is regarded as a potential efficient technology for the capture of anthropogenic carbon dioxide and the storage of hydrogen fuels.Compared with noble metal catalyst,Cu based catalysts are more widely studied because of lower price and stronger practicability.However,for as-fabricated supported metal catalyst,due to weak metal-support interactions and thus easy sintering of metallic copper particles and deactivation at high temperatures.Therefore,a Cu@Zr-CeO2 inverse catalyst with rich interface structure was constructed in this paper,which was applied to the hydrogenation of CO2 to methanol reaction.By changing the preparation method of the catalyst and the composition of composite metal oxides,the precise control of the surface interface structure could be realized.The specific work is as follows:(1)The Cu@Zr-CeO2 catalyst with inverse surrounding structure was prepared by micro-liquid film assisted coprecipitation method and compared with the catalysts prepared by co-precipitation method and impregnation method.The results showed that Cu@Zr-CeO2 catalyst had higher methanol selectivity and spatial temporal yield than the samples prepared by coprecipitation and impregnation methods.Various structural characterizations and in situ diffuse-reflectance infrared Fourier transform spectroscopy(DRIFTS)studies showed that the enhanced catalytic performance of Cu@ZrCeO2 catalyst was correlated with the formation of the highly dispersed active copper sites,abundant medium strength and strong basic sites,and favorable interfacial Cu+ sites,and Zr4+-Ov-Ce3+-like defective structures,accelerating transformation of formate intermediate and improving the methanol formation rate.(2)The Cu@Zr-CeO2 inverse catalyst with different Ce/Zr ratio was prepared by micro-liquid film assisted coprecipitation method and applied in the CO2 hydrogenation for methanol synthesis.Exploring the effects of Ce/Zr ratio on the structure and activity of the catalyst were investigated.The results show that due to the synergistic action between ZrO2 and CeO2 in the composite metal oxides,the Zr-Ce oxide solid solution is formed,which has abundant medium and strong base sites and Zr4+-Ov-Ce3+-like defect structure,which can promote the adsorption and activation of CO2 and the further hydrogenation of reaction intermediates.Moreover,there is a strong interaction between Cumetal oxide solid solution,which can form more Cu+-O-M-like(M=Ce,Zr)type interface structure,which can promote the hydrogenation of CO2 to methanol.This discovery provides a feasible strategy for the construction of highperformance Cu-based catalysts for CO2 hydrogenation to produce methanol.