吸附相反应技术制备MnOx/CeO2/SiO2催化剂及其低温选择性催化还原Nox

采用吸附相反应技术制备得到了MnO_x/CeO₂/SiO₂催化剂,通过X 射线衍射（XRD）、透射电子显微镜（TEM）、高分辨透射电子显微镜（HRTEM）、紫外激光拉曼（Raman）等手段对催化剂进行了表征. HRTEM分析表明活性组分MnO_x与CeO₂都均匀分布在载体SiO₂表面;XRD分析表明Mn₃O₄特征峰随着CeO₂含量的增加逐渐减小至完全消失,CeO₂的加入降低了MnO_x的结晶程度,增加了MnO_x的分散性;Raman光谱表明催化剂表面的Mn离子能够进入CeO₂晶格,激发出空穴氧,随着CeO₂负载量的增加,催化剂氧空穴浓度先升高后降低.以NH₃为还原剂,考评催化剂的NO_x低温选择性催化还原（SCR）性能,催化剂催化活性随CeO₂负载量增加先升高后降低,与催化剂氧空穴浓度变化规律一致,说明催化剂活性受氧空穴浓度影响,氧空穴浓度升高,催化剂催化活性升高.

MnOx/CeO2/SiO2 Catalysts Prepared by Adsorption Phase Reaction Technique for Selective Catalytic Reduction of NOx at Low-Temperature

MnO_x/CeO₂/SiO₂ catalysts were prepared by the adsorption phase reaction technique and were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and Raman spectroscopy. HRTEM showed that MnO_x and CeO₂ particles were uniformly coated on the surface of SiO₂. The XRD spectra showed that the intensity of the Mn₃O₄ diffraction peaks gradually decreased and then completely disappeared with the increasment of the CeO₂ content, which indicated that CeO₂ reduced the crystallinity of MnO_x and improved the dispersibility of MnO_x. Raman spectroscopy indicated that Mn ions on the surface of catalysts could enter into the lattice of CeO₂, replace oxygen ions, and form oxygen vacancies. With the increasment of CeO₂ content, the density of oxygen vacancies initially increased and then decreased. We used the catalysts for selective catalytic reduction (SCR) of NO_x with NH₃. The catalytic activity initially increased and then decreased with the increasment of CeO₂ content, similar to the change in the density of oxygen vacancies. Thus, the catalytic activity of the MnO_x/CeO₂/SiO₂ catalysts increases with increasing the density of oxygen vacancies.