In situ investigation of decomposing ammonia and ammonobasic solutions under supercritical conditions via UV/vis and Raman Spectroscopy
| Autor: | Thomas G. Steigerwald, Johannes Balouschek, Eberhard Schluecker, Anna-Carina L. Kimmel, Nicolas S. A. Alt, Benjamin Hertweck |
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| Rok vydání: | 2018 |
| Předmět: |
Materials science
General Chemical Engineering Inorganic chemistry 02 engineering and technology 010402 general chemistry 021001 nanoscience & nanotechnology Condensed Matter Physics 01 natural sciences Decomposition Supercritical fluid 0104 chemical sciences Catalysis Ammonia chemistry.chemical_compound symbols.namesake Ultraviolet visible spectroscopy chemistry Sodium amide symbols Physical and Theoretical Chemistry 0210 nano-technology Spectroscopy Raman spectroscopy |
| Zdroj: | The Journal of Supercritical Fluids. 134:96-105 |
| ISSN: | 0896-8446 |
| Popis: | An optical cell was used in this work, which allows spectroscopic measurements of fluids up to 600 °C and 300 MPa. The maximum pressure reached in this work was 254 MPa and the internal cell temperature was a maximum of 563 °C at a heating temperature of 617 °C. In the following, a combination of Raman and UV/vis spectroscopy was used for in situ investigation of the breakdown of sodium azide above 300 °C combined with the formation of sodium amide. It was verified that the breakdown of NaN3 occurs before the formation of NaNH2 starts. In a second step the decomposition of supercritical ammonia under ammonothermal conditions was investigated solely via Raman spectroscopy. The study comprises four different fluid compositions: pure ammonia, ammonia with a ruthenium catalyst, ammonia and mineralizer (sodium azide) and last ammonia, mineralizer and gallium nitride (GaN). By this, it was possible to proof that with pure ammonia and without a proper catalyst the decomposition of ammonia stops quite far before chemical equilibrium is reached. |
| Databáze: | OpenAIRE |
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