Performance For The Catalytic CO Oxidation Over The SnO₂-based Catalysts

In contemporary society,energy supply is mainly dominated by fossil fuels(coal,oil,and natural gas).As a result the environmental pollution problems become increasingly serious,and have negative impact on the human's daily life and social sustainable development.Carbon monoxide(CO)is a kind of toxic gas,which poses a huge threat to human life and health.Catalytic oxidation is an effective method to eliminate CO.In this paper,we investigate the influence of different carriers,SnO2 loading and preparation methods in the SnO2-based catalysts.SnO2 / Al2O3 model catalysts were prepared by physical mixing method,incipient wetness impregnation method and co-precipitation method for the catalytic CO oxidation.Compared to the other two methods,the catalysts prepared by physical mixing method presented excellent CO oxidation performance with the lowest activation energy(Ea = 40.6 kJ mol-1).The CO-TPR and CO-TPSR results suggested that the surface adsorption oxygen plays an important role upon CO oxidation.The kinetics results showed that the reaction pathways upon the SnO2-based catalysts for CO oxidation follow the Langmuir-Hinshelwood model.At high oxygen partial pressure,the reaction rate is mainly determined by the amount and the activity of oxygen vacancies.The oxygen storage capacity of the SnO2 / Al2O3 catalyst prepared by physical mixing method is 147.2 ?mol [O] g-1,which is nearly two times higher than that of the SnO2.The UV/ Vis absorption spectra results revealed that SnO2 and Al2O3 might form heterojunction structure in the catalyst,which led to the increase in the concentration of oxygen vacancies.Experimental results showed that the SnO2-based catalysts have good water resistance and the ability to recover quickly.Moreover,SnO2 catalysts with special morphologies were also synthesized with hydrothermal method.The influence of several major factors including precursor concentration,pH value,template type,hydrothermal temperature and hydrothermal time were investigated in the formation of SnO2 catalyst,and we achieved the SnO2 catalyst with stable nanorods cluster structure.The growth mechanism of SnO2 nanorods was discussed,and the activity of CO oxidation was also tested.