Promotion effect of residual K on the decomposition of N2O over cobalt-cerium mixed oxide catalyst

摘要

A series of cobalt-cerium mixed oxide catalysts(Co3O4-CeO2)with a Ce/Co molar ratio of 0.05 were prepared by co-precipitation(with K2CO3 and KOH as the respective precipitant),impregnation,citrate,and direct evaporation methods and then tested for the catalytic decomposition of N2O.XRD,BET,XPS,O2-TPD and H2-TPR methods were used to characterize the catalysts.Catalysts with a trace amount of residual K exhibited higher catalytic activities than those without.The presence of appropriate amount of K in Co3O4-CeO2 may improve the redox property of Co3O4,which is important for the decomposition of N2O.When the amount of K was constant,the surface area became the most important factor for the reaction.The co-precipitation-prepared catalyst with K2CO3 as precipitant exhibited the best catalytic performance because of the presence of ca.2 mol% residual K and the high surface area.We also discussed the rate-determining step of the N2O decomposition reaction over these Co3O4-CeO2 catalysts.