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Enhancement of Activity and Sulfur Resistance of CeO 2 Supported on TiO 2 –SiO 2 for the Selective Catalytic Reduction of NO by NH 3

2012; American Chemical Society; Volume: 46; Issue: 11 Linguagem: Inglês

10.1021/es3001773

1520-5851

Caixia Liu, Liang Chen, Junhua Li, Lei Ma, Hamidreza Arandiyan, Yu Du, Jiayu Xu, Jiming Hao,

Advanced Photocatalysis Techniques

A series of novel metal-oxide-supported CeO2 catalysts were prepared via the wet impregnation method, and their NH3–SCR activities were investigated. The Ce/TiO2–SiO2 catalyst with a Ti/Si mass ratio of 3/1 exhibited superior NH3–SCR activity and high N2 selectivity in the temperature range of 250–450 °C. The characterization results revealed that the activity enhancement was correlated with the properties of the support material. Cerium was highly dispersed on the TiO2–SiO2 binary metal oxide support, and the interaction of Ti and Si resulted in greater conversion of Ce4+ to Ce3+ on the surface of the catalyst compared to that on the single metal oxide supports. As a result of in the increased number of acid sites on Ce/TiO2–SiO2 that resulted from the addition of SiO2, the NH3 adsorption capacity was significantly improved. All of these factors played significant roles in the high SCR activity. More importantly, Ce/TiO2–SiO2 exhibited strong resistance to SO2 and H2O poisoning. After the addition of SiO2, the number of Lewis-acid sites was not decreased, but the number of Brønsted-acid sites on the TiO2–SiO2 carrier was increased. The introduction of SiO2 further weakened the alkalinity over the surface of the Ce/TiO2–SiO2 catalyst, which resulted in sulfate not easily accumulating on the surface of the Ce/TiO2–SiO2 catalyst in comparison with Ce/TiO2.