Study of Phase Transitions Occurring in a Catalytic System of ncFe-NH<sub>3</sub>/H<sub>2</sub> with Chemical Potential Programmed Reaction (CPPR) Method Coupled with In Situ XRD
Nitriding of nanocrystalline iron and reduction of nanocrystalline iron nitride with gaseous mixtures of hydrogen with ammonia were studied at 375 °C and atmospheric pressure using the chemical potential programmed reaction (CPPR) method coupled with in situ XRD. In this paper, a series of phase tra...
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MDPI AG
2021-01-01
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| author | Ewa A. Ekiert Bartłomiej Wilk Zofia Lendzion-Bieluń Rafał Pelka Walerian Arabczyk |
| author_facet | Ewa A. Ekiert Bartłomiej Wilk Zofia Lendzion-Bieluń Rafał Pelka Walerian Arabczyk |
| author_sort | Ewa A. Ekiert |
| collection | DOAJ |
| description | Nitriding of nanocrystalline iron and reduction of nanocrystalline iron nitride with gaseous mixtures of hydrogen with ammonia were studied at 375 °C and atmospheric pressure using the chemical potential programmed reaction (CPPR) method coupled with in situ XRD. In this paper, a series of phase transitions occurring during the processes is shown, and a detailed analysis of the phase composition and the structure of the material is given. The influence of a variable nitriding potential on the lattice parameters of α-Fe, γ′-Fe<sub>4</sub>N, and ε-Fe<sub>3-2</sub>N phases is shown. The α phase interplanar space changes irrelevantly in the one phase area but decreases linearly with average increases in crystallite size when α→γ′ transformation occurs. The nanocrystallite size distributions (nCSDs) were determined, with nCSD of the α phase for nitriding and nCSD of the ε phase for reduction. The reduction of the ε phase can occur directly to α or indirectly with an intermediate step of γ′ formation as a result of ε→γ′→α transformations. The determining factor in the reducing process method is the volume of ε phase nanocrystallites. Those with V < 90,000 nm<sup>3</sup> undergo direct transformation ε→αFe(N), and V > 90,000 nm<sup>3</sup> transforms to αFe(N) indirectly. It was determined at what value of nitriding potential which fraction of the ε phase nanocrystallites starts to reduce |
| first_indexed | 2024-03-09T06:19:52Z |
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| language | English |
| last_indexed | 2024-03-09T06:19:52Z |
| publishDate | 2021-01-01 |
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| spelling | doaj.art-8519fb6c8c6c45dd9d1b1f13847c8b562023-12-03T11:49:23ZengMDPI AGCatalysts2073-43442021-01-0111218310.3390/catal11020183Study of Phase Transitions Occurring in a Catalytic System of ncFe-NH<sub>3</sub>/H<sub>2</sub> with Chemical Potential Programmed Reaction (CPPR) Method Coupled with In Situ XRDEwa A. Ekiert0Bartłomiej Wilk1Zofia Lendzion-Bieluń2Rafał Pelka3Walerian Arabczyk4Department of Inorganic Chemical Technology and Environment Engineering, Faculty of Chemical Technology and Engineering, West Pomeranian University of Technology in Szczecin, Piastów Ave. 42, 71-065 Szczecin, PolandDepartment of Inorganic Chemical Technology and Environment Engineering, Faculty of Chemical Technology and Engineering, West Pomeranian University of Technology in Szczecin, Piastów Ave. 42, 71-065 Szczecin, PolandDepartment of Inorganic Chemical Technology and Environment Engineering, Faculty of Chemical Technology and Engineering, West Pomeranian University of Technology in Szczecin, Piastów Ave. 42, 71-065 Szczecin, PolandDepartment of Inorganic Chemical Technology and Environment Engineering, Faculty of Chemical Technology and Engineering, West Pomeranian University of Technology in Szczecin, Piastów Ave. 42, 71-065 Szczecin, PolandDepartment of Inorganic Chemical Technology and Environment Engineering, Faculty of Chemical Technology and Engineering, West Pomeranian University of Technology in Szczecin, Piastów Ave. 42, 71-065 Szczecin, PolandNitriding of nanocrystalline iron and reduction of nanocrystalline iron nitride with gaseous mixtures of hydrogen with ammonia were studied at 375 °C and atmospheric pressure using the chemical potential programmed reaction (CPPR) method coupled with in situ XRD. In this paper, a series of phase transitions occurring during the processes is shown, and a detailed analysis of the phase composition and the structure of the material is given. The influence of a variable nitriding potential on the lattice parameters of α-Fe, γ′-Fe<sub>4</sub>N, and ε-Fe<sub>3-2</sub>N phases is shown. The α phase interplanar space changes irrelevantly in the one phase area but decreases linearly with average increases in crystallite size when α→γ′ transformation occurs. The nanocrystallite size distributions (nCSDs) were determined, with nCSD of the α phase for nitriding and nCSD of the ε phase for reduction. The reduction of the ε phase can occur directly to α or indirectly with an intermediate step of γ′ formation as a result of ε→γ′→α transformations. The determining factor in the reducing process method is the volume of ε phase nanocrystallites. Those with V < 90,000 nm<sup>3</sup> undergo direct transformation ε→αFe(N), and V > 90,000 nm<sup>3</sup> transforms to αFe(N) indirectly. It was determined at what value of nitriding potential which fraction of the ε phase nanocrystallites starts to reducehttps://www.mdpi.com/2073-4344/11/2/183nanocrystalline iron catalystnanocrystalline iron nitridesCPPR methodin situ XRDammonia gaseous nitriding |
| spellingShingle | Ewa A. Ekiert Bartłomiej Wilk Zofia Lendzion-Bieluń Rafał Pelka Walerian Arabczyk Study of Phase Transitions Occurring in a Catalytic System of ncFe-NH<sub>3</sub>/H<sub>2</sub> with Chemical Potential Programmed Reaction (CPPR) Method Coupled with In Situ XRD Catalysts nanocrystalline iron catalyst nanocrystalline iron nitrides CPPR method in situ XRD ammonia gaseous nitriding |
| title | Study of Phase Transitions Occurring in a Catalytic System of ncFe-NH<sub>3</sub>/H<sub>2</sub> with Chemical Potential Programmed Reaction (CPPR) Method Coupled with In Situ XRD |
| title_full | Study of Phase Transitions Occurring in a Catalytic System of ncFe-NH<sub>3</sub>/H<sub>2</sub> with Chemical Potential Programmed Reaction (CPPR) Method Coupled with In Situ XRD |
| title_fullStr | Study of Phase Transitions Occurring in a Catalytic System of ncFe-NH<sub>3</sub>/H<sub>2</sub> with Chemical Potential Programmed Reaction (CPPR) Method Coupled with In Situ XRD |
| title_full_unstemmed | Study of Phase Transitions Occurring in a Catalytic System of ncFe-NH<sub>3</sub>/H<sub>2</sub> with Chemical Potential Programmed Reaction (CPPR) Method Coupled with In Situ XRD |
| title_short | Study of Phase Transitions Occurring in a Catalytic System of ncFe-NH<sub>3</sub>/H<sub>2</sub> with Chemical Potential Programmed Reaction (CPPR) Method Coupled with In Situ XRD |
| title_sort | study of phase transitions occurring in a catalytic system of ncfe nh sub 3 sub h sub 2 sub with chemical potential programmed reaction cppr method coupled with in situ xrd |
| topic | nanocrystalline iron catalyst nanocrystalline iron nitrides CPPR method in situ XRD ammonia gaseous nitriding |
| url | https://www.mdpi.com/2073-4344/11/2/183 |
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