钕改性铁基催化剂用于氮氧化物脱除

Neodymium-modified iron-based catalysts for nitrogen oxides removal

采用分步浸渍法,分两步将金属铁和钕依次引入商业化成品二氧化钛表面,研究其脱硝性能。通过X射线衍射(XRD)、氮气吸附-脱附(N2-BET)、X射线光电子能谱(XPS)、氨程序升温脱附(NH3-TPD)、氢气程序升温还原(H2-TPR)等方法对样品进行表征分析。通过氮气吸附-脱附发现,钕的引入使得负载铁后的催化剂比表面积减小。X射线衍射分析结果表明,引入的金属物种在催化剂表面具有良好的分散性。氨程序升温脱附测试结果显示,钕的引入增加了催化剂的总酸量,同时改变了催化剂的酸性分布。X射线光电子能谱测试结果表明,钕改性增加了催化剂表面吸附氧和铁(Ⅱ)的含量,有利于脱硝反应的进行。氢气程序升温还原测试结果表明,钕的引入使得催化剂氧化还原性能略有下降。活性测试结果表明,适量钕负载有利于提升催化剂的脱硝性能,钕元素在催化剂中的质量分数为9%时催化剂表现最优,最佳脱硝效率为81.4%。

Metal Fe and Nd were introduced into the surface of commercial TiO_(2) by stepwise impregnation to study its denitrification performance.The samples were characterized by X-ray diffraction(XRD),nitrogen adsorption-desorption(N_(2)-BET),X-ray photoelectron spectroscopy(XPS),ammonia temperature-programmed desorption(NH_(3)-TPD),hydrogen temperature-programmed reduction(H_(2)-TPR).The adsorption and desorption of N_(2)showed that the introduction of Nd reduced the specific surface area of the catalysts loaded with Fe.X-ray diffraction analysis showed that the introduced metal species had good dispersion on the catalyst surface.The results of NH_(3)-TPD test showed that the introduction of Nd increased the total acid content of the catalyst and changed the acid distribution of the catalyst.XPS results showed that Nd modification increased the content of oxygen and Fe^(2+)on the surface of the catalyst,which was beneficial to the denitrification reaction.H_(2)-TPR test showed that the introduction of Nd reduced the redox performance of the catalyst slightly.The results of activity test showed that appropriate Nd loading was beneficial to improve the denitrification performance of the catalyst.When the mass fraction of Nd element in the catalyst was 9%,the catalyst had the best denitrification efficiency of 81.4%.