Structural Design Of In₂O₃/ZrO₂ Binary Composite Oxides And Their Catalytic Performance In CO₂ Hydrogenation To Methano

The CO₂ hydrogenation to methanol process is an effective way to alleviate the greenhouse effect and the recycling of carbon resources.This process requires efficient catalysts to meet the technical requirements of high conversion,high selectivity and high stability.Due to the special interfacial interaction between In₂O₃-ZrO₂ bimetallic oxides,they exhibit high selectivity and stability in CO₂ hydrogenation to methanol,but this catalyst system still has much room for exploration in terms of improving CO₂adsorption activation and mechanism research.In this paper,we focus on the key factors affecting the catalytic hydrogenation of CO₂ to methanol by bimetallic oxides,and explore different synthetic strategies and modulation of the composition of the bimetallic composite oxides to construct In₂O₃/ZrO₂ with rich surface interface structure.The synergistic effects of the two phases of indium-zirconium were revealed by means of experimental characterization and theoretical calculations in order to provide ideas for the design of catalysts with high stability and catalytic activity.The specific research contents are as follows:（1）In₂O₃/ZrO₂ binary oxides were prepared by different synthesis methods with the aim of revealing the conformational relationship between the binary composite oxides and optimizing the component ratios to explore the relationship between the interfacial synergy of the two phases,oxygen vacancy defects and catalytic performance.The results showed that different composite methods affected the exposure of In₂O₃ components in the ZrO₂ phase.The largest In₂O₃ component exposure area(S_In=6.22 m²·g^-1)was found in the complexes made by the precipitation coating method.10%In₂O₃/ZrO₂-PC binary oxides exhibited excellent catalytic performance and stability due to the large In₂O₃ component exposure area and relatively abundant oxygen vacancy concentration.Under the conditions of T=573 K,P=5.0MPa,H₂:CO₂=3:1,and GHSV=18000 m L·g^-1_cat·h^-1,the CO₂ conversion was 7.5%,the methanol selectivity was 86%,and the methanol STY reached 0.398 g _{Me OH}·h^-1·g^-_cat¹,and the catalytic performance did not decay significantly within 120 h of reaction.The results of experiments and simulation calculations verified that the degree of In₂O₃surface exposure plays a key role in both CO₂ adsorption and activation,and stabilization of reaction intermediates.（2）Hollow spherical zirconium oxide（ZrO₂-B）was synthesized by the solvothermal method and used as a carrier to synthesize In₂O₃/ZrO₂-B binary composite oxides.The surface-interface structure of the composite oxides was adjusted by changing the preparation method and the molar ratio of the two-phase composition.Due to the interaction between the two phases,the excessive formation of oxygen vacancies in the composite oxides can be effectively suppressed,thus improving their CO₂ adsorption activation capacity and catalytic performance.Under the conditions of T=563 K,P=5.0 MPa,H₂:CO₂=4:1,GHSV=24000 m L·g^-1_cat·h^-1,the optimized40%In₂O₃/ZrO₂-BPC catalyst with optimal CO₂ conversion and methanol selectivity was obtained,with CO₂ conversion was 8.8%,methanol selectivity was 89%,and methanol STY up to 0.543g _{Me OH}·h^-1·g^-1_cat.The stability test showed that the catalyst showed no significant decay in catalytic performance within 120 h of reaction.The results of experiments and simulation calculations verified that too much or too little oxygen vacancy concentration would weaken the CO₂ adsorption activation.