The Role of Medium Acid Sites Tuned by Ce Adding in Moderate-Temperature NH.sub.3-SCR

• Published in: Catalysis letters 2022-08, Vol.152 (8), p.2270
• Main Authors: Bie, Xuan, Jiao, Kunling, Gong, Chunqin, Qu, Baozhong, Liu, Daokuan, Ma, Shuangchen
• Format: Article
• Language: English
• Subjects: Active oxygen; Analysis; Cerium; Electron transport; Nitrogen oxide
• ISSN: 1011-372X
• DOI: 10.1007/s10562-021-03797-0

To develop highly efficient NH.sub.3-SCR catalysts with a wide temperature range, catalysts based on MnAlO.sub.x and Cerium elements loading with various mixing ratios were prepared for selective catalytic reduction of NO by NH.sub.3. The special role of cerium was demonstrated by the surface structure characteristics and unique catalytic performance, involving the surface-active sites and compositions analysis. Interestingly, the strengthening of Mn.sub.1.2Al.sub.0.8Ce.sub.aO.sub.x on both acid sites, especially medium acids and strong acids, were clearly manifested. Meanwhile, the strong interaction between MnAlOx and CeO.sub.2 enabled favorable electron transfers from MnOx to CeO.sub.2 while generating more oxygen vacancies and active oxygen species, consequently accelerating the redox cycle. The results illustrate that the NOx conversion and the selectivity of N.sub.2 can be improved with more medium acids tuned by appropriate Ce adding. However, an opposite effect will appear by excessive addition. In addition, the reaction mechanisms at different acid sites are revealed. Our findings, therefore, provide a strategy for the rational design of moderate-temperature NH.sub.3-SCR catalysts through adding-induced component engineering of composite materials.