Thermodynamics of Chemical Processes in the System of Nanocrystalline Iron–Ammonia–Hydrogen at 350 °C
Nanocrystalline iron nitriding and the reduction of nanocrystalline iron nitrides in steady states at 350 °C are described using the chemical potential programmed reaction (CPPR), thermogravimetry (TG), <sup>57</sup>Fe Mössbauer spectroscopy (MS), and X-ray diffraction (XRD) methods. It...
| Main Authors: | , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2020-10-01
|
| Series: | Catalysts |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2073-4344/10/11/1242 |
| _version_ | 1797549675547459584 |
|---|---|
| author | Bartłomiej Wilk Artur Błachowski Zofia Lendzion-Bieluń Walerian Arabczyk |
| author_facet | Bartłomiej Wilk Artur Błachowski Zofia Lendzion-Bieluń Walerian Arabczyk |
| author_sort | Bartłomiej Wilk |
| collection | DOAJ |
| description | Nanocrystalline iron nitriding and the reduction of nanocrystalline iron nitrides in steady states at 350 °C are described using the chemical potential programmed reaction (CPPR), thermogravimetry (TG), <sup>57</sup>Fe Mössbauer spectroscopy (MS), and X-ray diffraction (XRD) methods. It was determined that during the process of nitriding of nanocrystalline iron, larger nanocrystallites formed the γ’ phase and the smallest nanocrystallites (about 4%) were transformed into the α” phase. Both phases were in chemical equilibrium, with the gas phase at the temperature of 350 °C. Stable iron nitride α” was also formed in the ε iron nitride reduction process. Taking the α” phase in the system of nanocrystalline Fe-NH<sub>3</sub>-H<sub>2</sub> into account, it was found that at certain nitriding potentials in the chemical equilibrium state, three solid phases in the nitriding process and four solid phases in the reduction process may coexist. It was also found that the nanocrystallites of ε iron nitride in their reduction process were transformed according to two mechanisms, depending on their size. Larger nanocrystallites of iron nitride ε were transformed into the α-iron phase through iron nitride γ’, and smaller nanocrystallites of ε nitride went through iron nitride α”. In the passivation process of nanocrystalline iron and/or nanocrystalline iron nitrides, amorphous phases of iron oxides and/or iron oxynitrides were formed on their surface. |
| first_indexed | 2024-03-10T15:17:50Z |
| format | Article |
| id | doaj.art-6e83d696502f4efca919bd93f54958fd |
| institution | Directory Open Access Journal |
| issn | 2073-4344 |
| language | English |
| last_indexed | 2024-03-10T15:17:50Z |
| publishDate | 2020-10-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Catalysts |
| spelling | doaj.art-6e83d696502f4efca919bd93f54958fd2023-11-20T18:45:02ZengMDPI AGCatalysts2073-43442020-10-011011124210.3390/catal10111242Thermodynamics of Chemical Processes in the System of Nanocrystalline Iron–Ammonia–Hydrogen at 350 °CBartłomiej Wilk0Artur Błachowski1Zofia Lendzion-Bieluń2Walerian Arabczyk3Department of Inorganic Chemical Technology and Environment Engineering, Faculty of Chemical Technology and Engineering, West Pomeranian University of Technology, Pułaskiego St. 10, 70-322 Szczecin, PolandMössbauer Spectroscopy Laboratory, Institute of Physics, Pedagogical University, Podchorążych St. 2, 30-084 Kraków, PolandDepartment of Inorganic Chemical Technology and Environment Engineering, Faculty of Chemical Technology and Engineering, West Pomeranian University of Technology, Pułaskiego St. 10, 70-322 Szczecin, PolandDepartment of Inorganic Chemical Technology and Environment Engineering, Faculty of Chemical Technology and Engineering, West Pomeranian University of Technology, Pułaskiego St. 10, 70-322 Szczecin, PolandNanocrystalline iron nitriding and the reduction of nanocrystalline iron nitrides in steady states at 350 °C are described using the chemical potential programmed reaction (CPPR), thermogravimetry (TG), <sup>57</sup>Fe Mössbauer spectroscopy (MS), and X-ray diffraction (XRD) methods. It was determined that during the process of nitriding of nanocrystalline iron, larger nanocrystallites formed the γ’ phase and the smallest nanocrystallites (about 4%) were transformed into the α” phase. Both phases were in chemical equilibrium, with the gas phase at the temperature of 350 °C. Stable iron nitride α” was also formed in the ε iron nitride reduction process. Taking the α” phase in the system of nanocrystalline Fe-NH<sub>3</sub>-H<sub>2</sub> into account, it was found that at certain nitriding potentials in the chemical equilibrium state, three solid phases in the nitriding process and four solid phases in the reduction process may coexist. It was also found that the nanocrystallites of ε iron nitride in their reduction process were transformed according to two mechanisms, depending on their size. Larger nanocrystallites of iron nitride ε were transformed into the α-iron phase through iron nitride γ’, and smaller nanocrystallites of ε nitride went through iron nitride α”. In the passivation process of nanocrystalline iron and/or nanocrystalline iron nitrides, amorphous phases of iron oxides and/or iron oxynitrides were formed on their surface.https://www.mdpi.com/2073-4344/10/11/1242nanocrystalline ironiron nitride α”CPPR methodMössbauer spectroscopyXRD methodthermodynamics |
| spellingShingle | Bartłomiej Wilk Artur Błachowski Zofia Lendzion-Bieluń Walerian Arabczyk Thermodynamics of Chemical Processes in the System of Nanocrystalline Iron–Ammonia–Hydrogen at 350 °C Catalysts nanocrystalline iron iron nitride α” CPPR method Mössbauer spectroscopy XRD method thermodynamics |
| title | Thermodynamics of Chemical Processes in the System of Nanocrystalline Iron–Ammonia–Hydrogen at 350 °C |
| title_full | Thermodynamics of Chemical Processes in the System of Nanocrystalline Iron–Ammonia–Hydrogen at 350 °C |
| title_fullStr | Thermodynamics of Chemical Processes in the System of Nanocrystalline Iron–Ammonia–Hydrogen at 350 °C |
| title_full_unstemmed | Thermodynamics of Chemical Processes in the System of Nanocrystalline Iron–Ammonia–Hydrogen at 350 °C |
| title_short | Thermodynamics of Chemical Processes in the System of Nanocrystalline Iron–Ammonia–Hydrogen at 350 °C |
| title_sort | thermodynamics of chemical processes in the system of nanocrystalline iron ammonia hydrogen at 350 °c |
| topic | nanocrystalline iron iron nitride α” CPPR method Mössbauer spectroscopy XRD method thermodynamics |
| url | https://www.mdpi.com/2073-4344/10/11/1242 |
| work_keys_str_mv | AT bartłomiejwilk thermodynamicsofchemicalprocessesinthesystemofnanocrystallineironammoniahydrogenat350c AT arturbłachowski thermodynamicsofchemicalprocessesinthesystemofnanocrystallineironammoniahydrogenat350c AT zofialendzionbielun thermodynamicsofchemicalprocessesinthesystemofnanocrystallineironammoniahydrogenat350c AT walerianarabczyk thermodynamicsofchemicalprocessesinthesystemofnanocrystallineironammoniahydrogenat350c |