Preparation Of Cerium-based Non-precious Metal Catalysts And Their Catalytic Activity For Co Reduction Of No

Nitric oxide (NO) and carbon monoxide (CO) are very harmful for natural and human, thus, the reseach of their elimination together have important practical significance. Because the high actitivty with some supported non-noble metals can matchwith precious metals in NO elimination, there is growing concern about the study in them. Otherwise, as an active support, CeO2 has been studied extensively in redox reaction for excellent oxygen storage capacity (OSC). In this dissertation, Cu and Ni as active species being supported on ceria-based oxide were studied on the NO+CO reaction performance.CuO-CeO2 was prepared by sol-gel (SG), deposition-precipitation (DP) and co-precipitation (CP), respectively. The addition of surfactant can enlarge the surface of the support, which can well disperse activity metal particles, and provide more oxygen vacansies for the reaction. After doping Sr or Zr into CeO2, Sr caused decrease in surface area, and resulted in activity reduction; but by CP preparation, the proper introduction of Zr improved redox property of Cu2+, lead to activity promotion.On the basis, a series of x%CuO-Ce0.9Zr0.1O2 and x%NiO-Ce0.9Zr0.1O2 catalysts were prepared by CP method. For Cu catalysts,35% NO conversion has been obtained over 11.5% CuO-Ce0.9Zr0.1O2 at 150℃.16%CuO-Ce0.9Zr0.1O2 also shows 100% N2 yield at high space velocity of 100,000 h-1 at 300℃. Here, being characterized by XRD, N2 adsorption, Raman, H2-TPR and NO-TPD techniques, the catalysts were studied of the structure and redox properties. The TPR profiles show that there are two main types of copper species participation in redox reaction, we consider that the crucial active species should be the finely dispersed CuO for the titled reaction in lower temperature range, and the presence of Cu2+ cations into lattice could activate in the high temperature range. However the content of copper into lattice is retained in the fluorite structure. In addition, the results of NO-TPD indicate that surface oxygen vacancies are activity sites of NO adsorption, where NO can be decompose to N2O and N2.And for x% NiO-Ce0.9Zr0.1O2 catalysts,16% NiO-Ce0.9Zr0.0O2 has the best activity, 28% NO conversion has been observed at 150℃, and 100% at 350℃,While the decline of the NO convention at low temperature which was found in excessive loading could attribute to the formation of cluster covering the active species.