Citric acid method was employed to prepare a series of Nb-promoted Fe_x-Nb₀._5-x-Ce_0.5 (x = 0.45, 0.4, 0.35) oxides for selective catalytic reduction with NH₃ (NH₃-SCR) of NO process. The structure, redox ability and reactivity of NH₃ and absorbed NO species on the catalysts were explored by using various characterization techniques such as X-ray diffraction (XRD), temperature program reduction with H₂ (H₂-TPR), temperature program desorption of NH₃ (NH₃-TPD), temperature program desorption of NO (NO-TPD), X-ray photoelectron spectroscopy (XPS) and in situ diffuse reflectance Fourier transform infrared spectroscopy (DRIFTS). It was found that the Nb promoted Fe_x-Nb₀._5-x-Ce_0.5 (x = 0.45, 0.4, 0.35) oxides catalysts showed outstanding NH₃-SCR of NO activity, excellent N₂ selectivity and remarkable SO₂/H₂O resistance, meanwhile, Fe_0.4-Nb_0.1-Ce_0.5 exhibited above 90% NO conversion in the range of 180–400 °C, together with near 100% N₂ selectivity. The characterization results point out that the excellent catalytic performance of Fe_0.4-Nb_0.1-Ce_0.5 can be ascribed to the strong interaction among Nb, Fe and Ce oxides. The strong interaction not only increases the BET surface area and redox ability of the catalyst, but also significantly improves the acid amount leading to the enhancement of the adsorption and activation of NH₃, which is advantage of the reactivity of adsorbed nitrate together with the adsorbed NH₃ species.

柠檬酸法用于制备一系列Nb促进的Fe _x -Nb ₀。_{5- x-} Ce _0.5（x  = 0.45，0.4，0.35 ）氧化物，用于用NO工艺的NH ₃（NH ₃ -SCR）选择性催化还原。利用X射线衍射（XRD），H ₂程序升温（H ₂ -TPR），程序升温脱附等多种表征技术，探索了催化剂上NH ₃和吸附的NO种类的结构，氧化还原能力和反应活性。NH ₃（NH ₃-TPD），NO的温度程序解吸（NO-TPD），X射线光电子能谱（XPS）和原位漫反射傅里叶变换红外光谱（DRIFTS）。发现Nb促进了Fe _x -Nb ₀。_{5- x} -Ce _0.5（x  = 0.45，0.4，0.35 ）氧化物催化剂显示出出色的NH ₃ -SCR的NO活性，出色的N ₂选择性和出色的SO ₂ / H ₂ O耐受性，同时，Fe _0.4 -Nb _0.1 -Ce _0.5在180–400°C的范围内表现出90％以上的NO转化，以及近100％的N₂选择性。表征结果表明，Fe _0.4 -Nb _0.1 -Ce _0.5的优异催化性能可归因于Nb，Fe和Ce氧化物之间的强相互作用。强烈的相互作用不仅增加了催化剂的BET表面积和氧化还原能力，而且显着提高了酸量，从而增强了NH ₃的吸附和活化，这具有吸附硝酸盐与被吸附物一起反应的优势。 NH ₃种。