Research On The Low-temperature Water-gas Shift Reaction Catalyzed By Ruthenium-based Catalysts Introduced With Ionic Liquids

Water gas shift(WGS)reaction is the key reaction in ammonia synthesis,hydrogen production,and adjustment of H2/CO in synthesis gas process.Especially for use in proton exchange membrane fuel cells(PEMFC),the WGS catalysts must be non-pyrophoric,active at low temperature,and stable during frequent shutdown-restart operation cycles.To meet these criteria,a reemergence of noble metal group based catalysts has occurred for their outstanding catalytic efficiency and stability,and various combinations are being used in low-temperature WGS reaction.In this paper,the preparation and optimization of Ru-based low-temperature WGS catalysts introduced ionic liquids(ILs)was studied.Firstly,3 kinds of different ways to introduce ILs to the catalysts preparation was investigated.We respectively studied the 2%Ru-2%Au/FeOx supported ionic liquids film catalysts by freeze-drying method,the 2%Ru-2%Au/FeOx catalysts by microwave synthesize method with ionic liquids,and 2%Ru/IL@SiO2 catalysts by sol-gel method.After the optimization of preparation conditions and parameters,we determined the Ru3(CO)12-IL@SiO2 catalysts prepared by sol-gel method as the best catalytic system.And the best volume concentration of tetraethyl orthosilicate(TEOS)was found to be 20%,the best molarity of HCl was 5 mol/L.In order to study the influence of different ILs on the catalytic performance of Ru3(CO)12-IL@SiO2 catalysts prepared by sol-gel method,we investigated 5 kinds of imidazolium ILs which includes[BDMIM]BF4、[BDMIM]NO3、[BDMIM]Cl、[BDMIM]OTf and[BDMIM]NTf2.We also further studied the effect of different IL loadings on the catalytic performance.The most suitable IL for WGS catalyst is[BDMIM]BF4 and the optimal IL loading is 30 wt.%,the prepared 2%Ru/[BDMIM]BF4@SiO2-30%catalystreached the highest CO conversion of 93.7%at 160 ℃.Furthermore,with the combination of phase and property characterization(includingXRD,TEM,SEM,TPD,TGA),surface composition and structure characterization(including IR,Specific surface area and pore structure measurement),we systematically studied the effect of different IL structures and different IL loadings on the catalytic performance of the Ru3(CO)12-IL@SiO2 catalysts.The experimental results proved that the SiO2 support with desired pore size and structure could be easily synthesized by using different IL structures and different IL loadings.The experimental results also provided significant insights into the influence of different IL structures and loadings on the textural structure of SiO2 support,dispersion of Ru complex,CO adsorption capacity,and catalytic activity.Such information can contribute to the development of a novel,highly active,stable low-temperature WGS catalysts.