Ce-based catalysts for simultaneous removal of both diesel soot and NO_x

Ce-based oxides were prepared by citric acid complex method and characterized by nitrogen physisorption, XRD, BET, H₂-TPR and XPS; their catalytic performances in simultaneous removal of diesel soot and NO_x were investigated on a thermogravimetric apparatus and a tubular reactor. Co_0.1/CeLa_0.05 prevailed over all the detected materials in catalytic performance for simultaneous removal of soot and NO_x. T₅₀ of this catalyst (temperature for 50% soot combustion)was 301℃, and the yield of N₂ was 41.4%. A majority of cobalt oxides were dispersed on the surface of Ce-La solid solution. The mutual transformation between Co³⁺ and Co²⁺enhanced the redox ability and oxygen storage capacity of pure ceria oxide, achieving lower temperature of combustion. Cerium-cobalt complex oxide doped with lanthanum presented a tremendous increase of surface area, leading to higher yield of N₂. The formation of trace amount of LaCoO₃ promoted oxygen vacancies creation, thus affecting positively to the soot combustion activity.