Mn MOF-derivatives synthesized based upon a mechanochemistry method for low-temperature NH3- SCR: From amorphous precursor to amorphous catalyst

• Published in: Molecular catalysis 2024-02, Vol.554, p.113767, Article 113767
• Main Authors: Li, Shimin, Li, Chuanqiang, Liu, Cui, Song, Liyun, Guo, Qiang, Peng, Tao, Chai, Qianqian, Zheng, Xuxu
• Format: Article
• Language: English
• Subjects: Acidic sites; Low-temperature NH3-SCR; Mechanochemical; Metal-organic frameworks; Surface defects
• ISSN: 2468-8231; 2468-8231
• DOI: 10.1016/j.mcat.2023.113767

•The target amorphous Mn metal-organic matrix materials were synthesized using a mechanical method.•Mn-BTC-BM-400 exhibited the best low temperature NH3-SCR performance due to its mixed system of amorphous and polycrystalline, which exposes more surface defects and acidic sites.•The results showed that the types and crystallinity of MnOx obtained from amorphous Mn-MOF precursors were different at different pyrolysis temperatures. Amorphous metal oxides have aroused extensive research interest in heterogeneous catalysis owing to their high surface area and rich surface defects. In this work, we synthesized a series of non-crystalline derivatives of Mn-BTC-BM MOF using a mechanochemical approach for NH3-selective catalytic reduction (SCR). The thermal decomposition of Mn-BTC-BM at 400gases yielded Mn (II, III) oxide (Mn-BTC-BM-400) with retained non-crystalline characteristics, which exhibited a smaller grain size and lower Mn-O bond energy than derivatives obtained through hydrothermal methods and other temperatures. This results in increased surface defects and acidic sites, promoting the release of lattice oxygen and leading to optimal low-temperature NH3-SCR activity. The Mn-BTC-BM-400 achieved an impressive 90 % conversion rate for NO at 170 ℃, and exhibited the lowest apparent activation energy (Ea=18 kJ/mol) among the six catalysts. This study presents a simple synthesis approach for non-crystalline MnOx catalysts, with mechanochemical synthesis offering promising improvements in catalytic performance. [Display omitted]