Reaction pathway of NOX reduction on a MnOX-CeO2 catalyst: An in-situ FTIR study
MnOX-CeO2 mixed oxide is a highly effective catalyst for NO reduction with NH3 in exhaust gases, demostrating excellent NO conversión and N2 selectivity at low temperatures. However, at high temperatures, both conversion and selectivity decline, leading to increased formation of N2O and NO2. To unde...
| Autores: | , , , , |
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| Tipo de documento: | artigo |
| Data de publicação: | 2025 |
| País: | España |
| Recursos: | Universidad del País Vasco |
| Repositório: | Addi. Archivo Digital para la Docencia y la Investigación |
| OAI Identifier: | oai:addi.ehu.eus:10810/73478 |
| Acesso em linha: | http://hdl.handle.net/10810/73478 |
| Access Level: | Acceso aberto |
| Palavra-chave: | nitrogen oxides selective catalytic reduction SCR reaction mechanism mixed oxide MnOX-CeO2 in-situ FTIR |
| Resumo: | MnOX-CeO2 mixed oxide is a highly effective catalyst for NO reduction with NH3 in exhaust gases, demostrating excellent NO conversión and N2 selectivity at low temperatures. However, at high temperatures, both conversion and selectivity decline, leading to increased formation of N2O and NO2. To understand this behavior, the reaction mechanism was investigated using in situ FTIR spectroscopy, which revealed two distinct pathways. At low temperatures, an Eley-Rideal mechanism dominates, where ammonia adsorbed on Lewis acid sites reacts with gas-phase NO, forming nitrosamine intermediates that rapidly decompose into N2 and H2O. At haigh temperatures, the Langmuir-Hinshelwood mechanism becomes predominant, involving the adsorption of both NH3 and NO, with NO indergoing oxidation to nitrate species before reacting with NH3-derived intermediates. The excessive deprotonation of adsorbed NH3 under these conditions leads to the formation of N2O as a by-product. These insights provide a deeper understanding of the temperature-dependent catalytic performance of MnOX-CeO2 in NO reduction. |
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