The Catalytic Performance And Kinetics Study Of CuO-SnO₂ Catalysts For Catalytic Oxidation Of CO

Carbon monoxide?CO?,which poses a huge threat to the life of human,plants and animals,is a common toxic gas.Catalytic oxidation is a promising way to eliminate CO emitted from cars and various industrial processes.SnO₂ is considered as a potential catalytic material because of its rich lattice oxygen defects.Previous reports have shown that CuO modified SnO₂ materials exhibit good catalytic performance for catalytic oxidation of CO.However,literatures about the active sites and reaction mechanism of CuO–SnO₂ catalysts are really limitted,both of which are still unclear.Herein,we investigated the catalytic oxidation of CO over the CuO–SnO₂catalysts prepared by facile co-precipitation method.Compared with the CuO and SnO₂ catalysts,all of the CuO–SnO₂ catalysts show higher CO oxidation activity.Especially,the SnCu30 catalyst shows the highest activity(the complete conversion temperature T_100°C=220°C),the lowest apparent activation energy(E_a=69.6 kJ mol^-1)and the highest reation rate,as well as the high water resistance.Comparing with the XRD,Raman,XAFS and H₂-TPR results of the SnCu30 catalyst before and after the nitric acid treatment,we found the existence of three kinds of copper species in the catalysts,i.e.,highly dispersed CuO,bulk CuO and incorporated copper in SnO₂ lattice.The XPS and in-situ DRIFTS results confirm the existence of Cu⁺species on the surface of the CuO–SnO₂ catalysts,which can provide the adsorption sites for CO.In addition,the anaerobic trititation and O1s XPS results display that the CuO–SnO₂ catalysts have the larger amount of surface lattice oxygen and higher oxygen storage capacity complete?OSCC?and the SnCu30 catalyst has the largest amount of surface lattice oxygen(O_latt./O_ads.=7.6)and highest OSCC value(OSCC=1009.9?mol[O]g^-1).Our kinetics results show that the reaction pathways upon catalytic oxidation of CO over the CuO–SnO₂ catalysts follow the Mars-van Krevelen model,and the highly dispersed CuO and the surface lattice oxygen species are the active sites for catalytic oxidation of CO.