铈钛掺杂促进铁氧化物低温SCR脱硝性能的机理

利用X射线晶格衍射（XRD）、N₂吸附和X射线光电子能谱仪（XPS）等对铈和钛掺杂后的铁氧化物晶相、孔隙结构及表面活性组分的分散度等物性进行表征分析，得到了铈和钛掺杂对铁氧化物低温NH₃-SCR脱硝性能的促进机理.结果表明：铈和钛掺杂会抑制铁氧化物中Fe₂O₃的结晶，细化其孔径，增大其比表面积和比孔容；铈掺杂会促使铁氧化物表面形成Ce⁴⁺/Ce³⁺氧化还原电子对；进一步掺杂钛会提高铁铈复合氧化物形成更多吸附氧，增强其表面低温催化氧化NO为NO₂的性能；且铈和钛掺杂增强了铁氧化物表面的吸附性能，尤其提高了对NH₃的低温吸附，从而促进了铁基氧化物催化剂的低温NH₃-SCR脱硝性能.

Promotional mechanism of cerium oxide and titanium oxide doping on the low-temperature NH3-SCR activity of iron oxide

X-ray diffraction, N₂ adsorption, X-ray Photoelectron Spectroscopy and so on were used to characterize the catalysts surface crystallite, the structure and the active species dispersion of iron oxide after the doping of cerium oxide and titanium oxide. And the promotional mechanism of the low-temperature NH₃-SCR activity over iron-based mixed oxide was revealed. The results indicated that the addition of cerium oxide and titanium oxide suppressed the formation of Fe₂O₃ crystallite in iron oxide and refined its pore size, and then increased the BET surface area and the pore volume of iron oxide. The oxideation-reduction electron pair of Ce⁴⁺ and Ce³⁺ was formed within iron oxide after the doping of cerium oxide. This made a large of adsorbed oxygen formed on the surface of iron-cerium mixed oxide catalyst, and enhanced its low-temperature catalytic oxidation of NO to NO₂. Moreover, the adsorption strength of NH₃ on the surface of iron oxide was enhanced after the doping of cerium oxide and titanium oxide, especially the low-temperature adsorption strength of NH₃. These contributed to improve the low-temperature NH₃-SCR activity over iron-based mixed oxides catalysts.