Study On The Preparation And Regulation Of Cerium Oxide-based Catalysts And Catalytic Carbon Dioxide Hydrogenation To Methano

Currently,the preparation of methanol from CO₂ is of great importance in CO₂recycling and greenhouse gas emission reduction,and this process needs to meet the technical requirements of catalyst cost,high selectivity,and high stability.Metal oxide-based catalysts have received much attention in recent years due to their high-temperature stability and low price.Moreover,due to its highly tunable structure,it has a large scope for exploration in the preparation of methanol by CO₂ hydrogenation.In this paper,the experiments focus on several factors affecting the CO₂-catalyzed hydrogenation of cerium oxide-based catalysts to methanol,and the conformational relationships of the composite catalysts are used as a starting point to explore different two compared with different synthesis strategies,specifically to investigate the effects of interfacial effects of Zn O-CeO₂ and MoS₂@CeO₂ catalysts on the catalyst structure and catalytic performance.The specific studies are as follows:（1）Zn O-CeO₂ systemA series of x%Zn O-CeO₂（Zn to metal element molar ratio）catalysts were synthesized after selecting the optimal synthesis strategy to investigate the conformational relationship between Zn O-CeO₂ catalysts and Zn O-CeO₂ binary oxides.The relationships between Zn O and Zn-Ce solid solution,oxygen vacancies,hydrogen spillover capacity,and catalytic capacity were explored.The results showed that the 30%Zn O-CeO₂ catalyst synthesized by the co-precipitation method had the best catalytic performance.The 30%Zn O-CeO₂ catalyst showed a CO₂ conversion of 4.61%,a methanol selectivity of 80.64%,and a methanol time dependence of 80.64%at T=573K,P=4.0 Mpa,H₂/CO₂=3:1,and GHSV=19600 m L/g_cat.^-1h^-1.80.64%,and the temporal yield of methanol was 0.244 g _{Me OH}h^-1g_cat.^-1.After the analysis by XRD,SEM,TEM,BET,and EPR with XPS,it was found that the introduction of Zn could obtain a higher oxygen vacancy concentration,which was beneficial to enhance the CO₂ adsorption capacity of CeO₂.When the addition of Zn reached 30%,the excess Zn formed a Zn O phase on the catalyst surface,which significantly enhanced the H₂ adsorption capacity.This dual functional site of Zn O and Zn O-CeO₂ can jointly promote the conversion of CO₂ to methanol.（2）MoS₂@CeO₂ systemMoS₂@CeO₂ was prepared by compounding MoS₂ with CeO₂ and using several different compounding methods,and a series of CeO₂ nanocarriers with different morphologies such as rods,cubes,hollow spheres,and nanoparticles were also synthesized according to the characteristics of different morphologies of CeO₂ exposing different crystalline surfaces,to explore the effects of different morphologies of CeO₂on the catalytic reaction,between the sulfur vacancies of molybdenum sulfide needing to be activated by reduction under The effect of different reduction conditions on the catalyst was also explored,and the relationship between the interfacial effect between the two phases,oxygen vacancies,CO₂ adsorption capacit,y and the evaluated effect was investigated.The results showed that the catalyst synthesized using hollow spherical CeO₂ had the best catalytic performance with a CO₂ conversion of 1.90%and a methanol selectivity of 90.41%at T=473 K,P=5.0 Mpa,H₂/CO₂=3:1 and GHSV=14400 m L/g_cat.^-1h^-1.A good synergistic effect between MoS₂ and CeO₂ was observed by XRD,SEM,TEM,BET,and EPR with XPS,and the analysis was due to the formation of a bifunctional active site of H₂-CO₂ by MoS₂ and CeO₂,which promoted the methanol production,while the hollow spherical CeO₂ could play a supporting role for MoS₂ to stabilize the catalyst structure and produce more oxygen vacancies.