Fe对Mn/CeO_2-TiO_2催化剂低温NH_3选择性催化还原NO的影响

Effect of Fe on the Selective Catalytic Reduction of NO by NH_3 at Low Temperature over Mn/CeO_2-TiO_2 Catalyst

以锰氧化物为活性组分,CeO2-TiO2为载体制备了Mn/CeO2-TiO2催化剂.考察了Fe的加入对Mn/CeO2-TiO2的低温NH3-SCR活性的影响.并采用BET比表面积,H2程序升温还原(H2-TPR)和X射线光电子能谱(XPS)等手段对催化剂进行了表征.活性结果表明,Fe的引入显著改善了Mn/CeO2-TiO2的NH3-SCR活性,催化剂在113～250℃之间表现出良好的NO去除效率.表征结果表明,Fe的引入促进了锰物种在CeO2-TiO2表面的分散,降低了Mn-Fe/CeO2-TiO2中锰物种的还原温度.XPS分析指出Mn-Fe/CeO2-TiO2表面Mn以+4价存在,而Fe主要以+3价的Fe2O3存在,且Fe与载体表面间存在强相互作用.

The Mn/CeO2-TiO2 catalyst was prepared using manganese oxide as active component, CeO2-TiO2 as support. Effect of the addition of Fe on the performance of NH3-SCR over Mn/CeO2-TiO2 at low temperature was investigated. These catalysts were characterized by BET surface area, H2 temperature programmed reduction （H2-TPR） and X-ray photoelectron spectroscope （XPS）. The activity result shows that the SCR performance of Mn/CeO2-TiO2 is obviously enhanced by the introduction of Fe. The Mn-Fe/CeO2-TiO2 catalyst shows high NO conversion within a wide temperature range of 113-250℃. The characterization results show that the introduction of Fe promotes the dispersion of manganese species on the surface of CeO2-TiO2, and the reduction temperature of manganese species shifts to lower temperature. The XPS analysis indicates that the valence of surface Mn on Mn-Fe/CeO2-TiO2 is ＋4, while the Fe mainly exists as ＋3 of Fe203, and the strong interaction happens between the Fe and the support.