Ammonia Desorption Peaks Can Be Assigned to Different Copper Sites in Cu/SSZ-13
| Autor: | Krishna Kamasamudram, Kunpeng Xie, Ashok Kumar, Louise Olsson, Kirsten Leistner |
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| Rok vydání: | 2017 |
| Předmět: |
Chabazite
Ion exchange Inorganic chemistry chemistry.chemical_element 02 engineering and technology General Chemistry Activation energy 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences Copper Catalysis 0104 chemical sciences chemistry.chemical_compound SSZ-13 chemistry Desorption 0210 nano-technology Organometallic chemistry |
| Zdroj: | Catalysis Letters. 147:1882-1890 |
| ISSN: | 1572-879X 1011-372X |
| DOI: | 10.1007/s10562-017-2083-8 |
| Popis: | The purpose of this study is to attribute NH3-TPD peaks observed over Cu/SSZ-13 catalysts to different catalytic sites. This is done by comparing a large number of copper loadings, especially below 40% ion exchange, to be able to see effects relevant to sites in both 6-membered and 8-membered rings. We found that intermediate (200–300 °C) and high (400–500 °C) temperature NH3-TPD peaks followed similar trends to the copper species in 6-membered and 8-membered rings respectively, as seen by H2-TPR and NO-DRIFTS. Thus we propose that these two TPD peaks represent ammonia stored on H and Cu sites in 6 and 8-membered rings, respectively. This assignment is further supported by the finding that the intermediate and high temperature NH3-TPD peaks of samples with different Si/Al ratios also follow the same trend. Moreover, we observe that the activation energy for ammonia oxidation is significantly lower for Cu in 6MR compared to Cu in 8MR rings. |
| Databáze: | OpenAIRE |
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