New insights into MnCe(Ba)O /TiO2 composite oxide catalyst: Barium additive accelerated ammonia conversion
| Autor: | Yuesong Shen, Bingxu Lu, Yan Ding, Yanwei Zeng, Youchun Pan, Xin Xu, Qijie Jin |
|---|---|
| Rok vydání: | 2021 |
| Předmět: |
Inorganic chemistry
chemistry.chemical_element Barium Selective catalytic reduction 02 engineering and technology General Chemistry 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences Redox 0104 chemical sciences Catalysis Ammonia chemistry.chemical_compound Adsorption chemistry Geochemistry and Petrology Lewis acids and bases 0210 nano-technology NOx |
| Zdroj: | Journal of Rare Earths. 39:532-540 |
| ISSN: | 1002-0721 |
| Popis: | MnCeOx/TiO2 has been widely used in selective catalytic reduction (SCR) of NOx at low temperature. However, it is often poisoned in the presence of water vapor and sulfur dioxide. In this work, the promotion mechanism of Ba modification was investigated. Results show that the doped BaO reacts with CeO2 and forms BaCeO3. This unique perovskite structure of BaCeO3 significantly enhances NO oxidation and NH3 activation of MnCeOx/TiO2 catalyst so that the NO conversion and the resistances to SO2 improve. It is found that Ba species obviously promotes the NO adsorption ability and improve the redox properties of MnCeOx/TiO2 catalyst. While the acid properties of the catalyst are inhibited by Ba modification and among which Lewis acid sites are dominant for both MnCeOx/TiO2 and MnCe(Ba)Ox/TiO2 catalysts. Furthermore, in situ DRIFT experiments reveal that the NO reduction upon MnCeOx/TiO2 and MnCe(Ba)Ox/TiO2 catalysts follows both E-R and L-H mechanisms, in which L-H is preferred. Ba species enhances the formation of active nitrate species, which accelerates the NO reduction through L-H mechanism. It is interesting that although Ba species weakens the NH3 adsorption, it induces the ammonia conversion to coordination ammonia, which in turn accelerates the catalytic reaction. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|
Full Text from ScienceDirect