Study On Preparation Of Rare Earths Modified SnO₂and Their Catalytic Oxidation Performance On CO And CH₄Oxidation

SnO2is an n-type semiconductor, which is widespread used in gas sensors, catalytic materials and semiconductor materials. Because of its surface oxygen species, SnO2is attracted more attention. When mixed with other metal, it would inform new co-oxides, which shows more obvious catalytic activity. The catalytic of catalysts is related to the surface oxigens of SnO2.With SnCl4·5H2O and Ce(NO3)3·6H2O as raw material, Sn-Cel2、Sn-Cell and Sn-Ce21samples were prepared by coprecipitation method. CO and CH4oxidation were used as probe reaction to examine the catalytic activity. Also, N2-BET、XRD and H2-TPR were used to characterize the structure and performance of the catalysts.A series of different molar ratios was analysed in detail. In order to find the best molar ratio which has better activity for CO and CH4oxidation, Sn-Ce91, Sn-Ce73, Sn-Ce55, Sn-Ce37, Sn-Cel9were prepared by coprecipitation method. Finally, we found that the catalyst of Sn-Ce73had the best activity.Catalysts prepared by different methods such as impregnation, sol-gel were used to prepared and used to CO and CH4oxidation, which were used to compare with chemical coprecipitation method.Different rare earths such as lanthanum, cerium and yttrium were used to modified SnO2with the2/1atomic ratio prepared by coprecipitation method. We found that cerium showed higher activity for CO and CH4oxidation because it formed solid solution. However, lanthanum and yttrium modified samples formed steady composite oxides, which were impeded for catalytic oxidation.The carrier of SnO2and CeO2were prepared CeO2/SnO2and SnO2/CeO2catalysts and then used in CH4catalytic oxidation. The results found that the carried catalyst had better catalytic performance than pure carriers, also CeO2/SnO2was better than SnO2/CeO2.