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

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, O-2-TPD and H-2-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 NO. When the amount of K was constant, the surface area became the most important factor for the reaction. The co-precipitation-prepared catalyst with KCO3 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 N,O decomposition reaction over these CO3O4-CeO2 catalysts. (c) 2007 Elsevier B.V. All rights reserved