CO + H/sub 2/ reaction over nitrogen-modified iron catalysts. Quarterly technical progress report, January 1-March 31, 1984
We have found that the nitride catalysts lose substantial amounts of nitrogen during the initial minutes of Fischer-Tropsch synthesis. In order to further study the stability of these catalysts, we have concentrated on the decomposition of the nitride in hydrogen. In addition, we have prepared a range of epsilon-Fe/sub x/N (2 < x < 3) phases. The Moessbauer parameters from these phases will aid in the identification and fitting of the transient epsilon phases formed during the carburization of Xi-Fe/sub 2/N. Extremely rapid nitrogen loss has been observed from Xi-Fe/sub 2/N in H/sub 2/ at 523 K both in constant velocity Moessbauer and in transient mass spectrometer experiments. In order to study the phase change from Xi-Fe/sub 2/N to ..cap alpha..-Fe in more detail, the hydrogenation temperature was decreased to 473 K and intermediate samples were quenched in liquid nitrogen to lock in the phase distribution for subsequent Moessbauer study. The spectra show complete conversion to ..cap alpha..-Fe at or before 21 minutes at 473 K. The intermediate samples show evidence of an extremely sharp gradient; only a very small amount of ..gamma..' or epsilon phase is observed. Thus, a moving front model of the phase transformation appears to be appropriate. Mass spectroscopy of the hydrogenation of Xi-Fe/sub 2/N at 523 K showed similar behavior to that of both the ..gamma..' and epsilon phases, in which an active surface species and a slowly activating one were observed. The H/sub 2/ was replaced by D/sub 2/ in this experiment in order to observe partially hydrogenated surface species in the initial spike of ammonia. All NH/sub x/D/sub y/ (x + y = 3) species were observed in this spike, indicating extremely rapid surface H/D exchange with gaseous ammonia. The fragmentation pattern of NH/sub 3/ in the mass spectrometer was also determined and will be used to calculate initial NH/sub x/ surface contributions. 23 references, 3 figures, 3 tables.
- Research Organization:
- Purdue Univ., Lafayette, IN (USA)
- DOE Contract Number:
- FG22-82PC50804
- OSTI ID:
- 6764491
- Report Number(s):
- DOE/PC/50804-6; ON: DE84014466
- Country of Publication:
- United States
- Language:
- English
Similar Records
CO + H/sub 2/ reaction over nitrogen-modified iron catalysts. Quarterly technical progress report, October 1, 1983-December 30, 1983. [Denitriding of iron nitrides in both hydrogen and helium]
CO + H/sub 2/ reaction over nitrogen-modified iron catalysts. Quarterly technical progress report, April 1-September 30, 1985
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CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CARBURIZATION
CATALYSTS
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL REACTIONS
DATA
ELEMENTS
EXPERIMENTAL DATA
FISCHER-TROPSCH SYNTHESIS
HARDENING
HIGH TEMPERATURE
HYDROGEN
HYDROGENATION
INFORMATION
IRON COMPOUNDS
IRON NITRIDES
MASS SPECTROSCOPY
MOESSBAUER EFFECT
NITRIDES
NITROGEN COMPOUNDS
NONMETALS
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
PHASE TRANSFORMATIONS
PNICTIDES
RESEARCH PROGRAMS
SPECTROSCOPY
STABILITY
SURFACE HARDENING
SURFACE TREATMENTS
TEMPERATURE DEPENDENCE
TRANSITION ELEMENT COMPOUNDS