Identifying the location of Cu ions in nanostructured SAPO-5 molecular sieves and its impact on the redox properties
| Autor: | Armin Hoell, Suresh Gatla, Jörg Radnik, Vikram Singh Raghuwanshi, Thi Thuy Hanh Dang, Dragomir Tatchev |
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| Rok vydání: | 2019 |
| Předmět: |
Materials science
Argon General Chemical Engineering Inorganic chemistry chemistry.chemical_element 02 engineering and technology General Chemistry 010402 general chemistry 021001 nanoscience & nanotechnology Molecular sieve 01 natural sciences Redox ASAXS XAS catalyst nanostructures Hydrothermal circulation 0104 chemical sciences law.invention X-ray absorption fine structure chemistry X-ray photoelectron spectroscopy law Crystallization 0210 nano-technology Spectroscopy |
| Zdroj: | 'RSC Advances ', vol: 9, pages: 6429-6437 (2019) |
| ISSN: | 2046-2069 |
| DOI: | 10.1039/c8ra10417d |
| Popis: | Combining X ray Absorption Fine Spectroscopy XAFS with Anomalous Small Angle X ray Scattering ASAXS determines the location of Cu2 ions in silicoaluminophosphate SAPO 5 frameworks prepared by hydrothermal crystallization or impregnation. As expected, for the hydrothermally prepared sample, incorporation in the SAPO 5 framework was observed. For the first time preferential location of Cu2 ions at the inner and outer surfaces of the framework is determined. Temperature Programmed Reduction TPR and X ray Photoelectron Spectroscopy XPS investigations demonstrated that such Cu2 is stable in an argon Ar atmosphere up to 550 C and can only be reduced under a hydrogen atmosphere. In contrast, Cu2 deposited by impregnation on the pure SAPO 5 framework can be easily reduced to Cu in an Ar atmosphere. At lower Cu amounts, mononuclear tetrahedrally coordinated Cu species were formed which are relatively stable in the monovalent form. In contrast, at higher Cu amounts, CuO particles were found which change easily between the mono and bivalent species |
| Databáze: | OpenAIRE |
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