Silica-supported iron nitride in Fischer-Tropsch reactions: I. Characterization of the catalyst

• Published in: Journal of catalysis 1985, Vol.91 (2), p.231-240
• Main Authors: Yeh, E., Jaggi, N.K., Butt, J.B., Schwartz, L.H.
• Format: Article
• Language: English
• Subjects: Catalysis; Catalysts: preparations and properties; Catalytic reactions; Chemistry; Exact sciences and technology; General and physical chemistry; General. Nomenclature, chemical documentation, computer chemistry; Theory of reactions, general kinetics; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry
• ISSN: 0021-9517; 1090-2694
• DOI: 10.1016/0021-9517(85)90337-9

The techniques of Mössbauer effect spectroscopy and wide angle X-ray diffraction have been applied to characterize nitrided iron catalysts (initial composition ≈ Fe 2N) supported on silica gel and used in the synthesis reaction. Mössbauer spectroscopy shows that the nitride catalyst becomes iron-rich during the first 3 h of reaction in the syngas environment (CO: H 2 = 1:3, T = 250 °C, 7.8 atm) indicating that nitrogen atoms are removed more rapidly by H 2 than they are simultaneously replaced by carbon atoms. After 3 h carburization becomes dominant, the carbon concentration increases, and the catalyst composition stabilizes after about 18 h of reaction. The analysis of the 4.2 K Mössbauer spectrum and X-ray diffraction of an equilibrated catalyst after 49 h of reaction gives a composition of Fe 2.18C 1 − y N Y , where y was estimated to be between 0.13 and 0.20.