Preparation Of MeCeO_x Solid Solution Catalyst And Its Catalytic Synthesis Of Dimethyl Carbonate

Focusing on the process of direct synthesis of dimethyl carbonate by CO₂ methanol method,in view of the technical bottleneck of the low reaction efficiency of the existed fixed-bed heterogeneous catalytic system,in view of the spontaneous solid solution characteristics of CeO2,based on the special oxygen vacancy activation mechanism of the bimetal oxide solid solution structure and The interfacial synergistic effect of dual active sites.The paper proposes to adopt a liquid phase co-precipitation process,with In2O3,Fe2O3,Co2O3,CuO,Ni2O3 and ZrO2 as doping modifiers,to develop a series of MeCeO_x（In,Fe,Co,Cu,Ni and Zr）Research work on the preparation,characterization and catalytic performance evaluation of bimetal oxide solid solution structure catalystsThe liquid phase co-precipitation method was used to investigate the catalytic performance of a series of MeCeO_x bimetallic oxide solid solution structure catalysts,with the help of XRD,O2-TPO,H2-TPR,CO₂-TPD and CH₃OH-TPD and other means of catalyst physical and chemical properties Analyze and characterize,and establish the structure-activity relationship of the catalyst.The research results show that the doping of different metal oxides has a greater impact on the physicochemical properties and catalytic performance of MeCeO_x（Me=Fe,Co,Ni,Cu,Zr,In）solid solution structured catalysts.Compared with pure CeO2,doping modification All have improved the adsorption capacity of CO₂ molecules,but the adsorption capacity of CoCeO_x,NiCeO_x and CuCeO_x on methanol molecules has been weakened;Compared with ZrCeO_x,InCeO_x catalyst exhibits higher oxygen mobility and stronger bimetallic synergy due to its autogenous solid solution characteristics;Catalytic evaluation results showed that FeCeO_x,CoCeO_x,NiCeO_x and CuCeO_x catalytic systems did not produce dimethyl carbonate,but CeO2,ZrCeO_x and InCeO_x catalysts all showed certain catalytic activity,and the activity relationship was InCeO_x>ZrCeO_x>CeO2 Combined with the results of diffuse reflectance Fourier transform infrared spectroscopy（DRIFTS）in-situ analysis,in the cerium-based bimetal oxide catalytic reaction system,the solid solution structure catalyst based on the synergistic effect of oxygen vacancy activation CO₂ and dual active sites is double coordinated The effective combination of bicarbonate and monocoordinated methyl to form an intermediate monomethyl carbonate（MMC）is the key to the selective production of the target product dimethyl carbonateWith the help of XRD,XPS,BET,HRTEM,O2-TPO,CO₂-TPD and CH₃OH-TPD and other analysis and characterization methods,the preparation factors such as the doping amount of In2O3,the type of precipitant and the roasting temperature have been systematically investigated for the solid solution of InCeO_x bimetallic oxide.The results of the study showed that the co-precipitation process was used to prepare 10%InCeO_x bimetallic oxide with 10%In2O3 content,ammonia as the precipitant,and calcination at 400℃ for 4 hours（specific surface area 142.5m2/g,total pore volume 0.2cm3 g-1）,at the same time,it had a rich oxygen vacancy defect concentration of 24.5%and a higher oxygen mobility,showing the largest adsorption of CO₂ and CH₃OH reaction molecules;at a reaction pressure of 1.5Mpa,Temperature 140℃,GHSV=3600mL/g·h,10%InCeO_x bimetal oxide solid solution structure catalyst showed good catalytic performance,methanol conversion rate,dimethyl carbonate selectivity and space yield rate STY respectively Up to 4.3%,91.4%and 0.056gDMC·h-1gcat-1.