The Role of Medium Acid Sites Tuned by Ce Adding in Moderate-Temperature NH3-SCR

• Published in: Catalysis letters 2022-08, Vol.152 (8), p.2270-2279
• Main Authors: Bie, Xuan, Jiao, Kunling, Gong, Chunqin, Qu, Baozhong, Liu, Daokuan, Ma, Shuangchen
• Format: Article
• Language: English
• Subjects: Acids; Ammonia; Catalysis; Catalysts; Cerium oxides; Chemical reduction; Chemistry; Chemistry and Materials Science; Composite materials; Industrial Chemistry/Chemical Engineering; Mixing ratio; Organometallic Chemistry; Oxygen; Physical Chemistry; Reaction mechanisms; Selective catalytic reduction; Selectivity; Strong interactions (field theory); Surface structure
• ISSN: 1011-372X; 1572-879X
• DOI: 10.1007/s10562-021-03797-0

To develop highly efficient NH 3 -SCR catalysts with a wide temperature range, catalysts based on MnAlO x and Cerium elements loading with various mixing ratios were prepared for selective catalytic reduction of NO by NH 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 1.2 Al 0.8 Ce a O x on both acid sites, especially medium acids and strong acids, were clearly manifested. Meanwhile, the strong interaction between MnAlOx and CeO 2 enabled favorable electron transfers from MnOx to CeO 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 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 3 -SCR catalysts through adding-induced component engineering of composite materials. Graphic Abstract Mn 1.2 Al 0.8 Ce a O x Catalysts with different surface features were fabricated by an environment-friendly method. The strong interaction between MnAlOx and CeO 2 was systematically illustrated. Meanwhile, the importance of medium acids was convincingly revealed. And the reaction mechanisms at different acid sites were demonstrated. These provide a strategy for the rational design of moderate-temperature NH 3 -SCR catalysts through adding-induced component engineering of composite materials.