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]
The synthesis of epsilon-Fe/sub 2.7/N is confirmed by Moessbauer spectroscopy. Carburization of epsilon-iron nitride for 2.5 hours in 3H/sub 2//CO at 523 K starts the formation of a bulk structure similar to that seen during ..gamma..'-iron nitride carburization. Reaction of ..gamma..'-Fe/sub 4/N in 3CO/H/sub 2/ synthesis gas at 523 K shows a better bulk stability than reaction in 3H/sub 2//CO. Kinetic analysis of the product distribution at the higher CO ratio confirms greater activity and selectivity maintainance. The kinetics of denitriding in both He and H/sub 2/ was studied with a mass spectrometer. Extremely rapid nitrogen loss was observed from both ..gamma..'-Fe/sub 4/N and epsilon-Fe/sub 2.7/N catalysts in H/sub 2/ at 523 K. In both cases a initial exposure to H/sub 2/ produced a significant amount of NH/sub 3/ which we ascribe to an active surface species. Hydrogenation of the bulk continued with a slow rise to a maximum about 90 seconds after the introduction of H/sub 2/. The denitriding activity of the epsilon-Fe/sub 2.7/N catalyst was significantly higher than that of the ..gamma..'-Fe/sub 4/N catalyst. In contrast, the denitriding rate of epsilon-Fe/sub 2.7/N in He was significantly slower than that in H/sub 2/ until high temperatures (773K) were reached. An overall activation energy of 41.5 kcal/mol was obtained for this process. Comparison of the denitriding rate of virgin epsilon-Fe/sub 2.7/N in H/sub 2/ with that of the same nitride after five minutes of carburization during the hydrocarbon synthesis reaction indicates large differences in the overall rate. The carburized nitride was some 300 times less active to bulk hydrogenation than the virgin catalyst, which is indicative of significant changes in the first few layers of the nitride during the initial minutes of the synthesis reaction. 17 references, 5 figures.
- Research Organization:
- Purdue Univ., Lafayette, IN (USA)
- DOE Contract Number:
- FG22-82PC50804
- OSTI ID:
- 5317889
- Report Number(s):
- DOE/PC/50804-5; ON: DE84009046
- Country of Publication:
- United States
- Language:
- English
Similar Records
Surface and bulk changes in iron nitride catalysts in H sub 2 /CO mixtures
CO + H/sub 2/ reaction over nitrogen-modified iron catalysts. Quarterly technical progress report, January 1-March 31, 1984
Related Subjects
010405 -- Coal
Lignite
& Peat-- Hydrogenation & Liquefaction
090121* -- Hydrocarbon Fuels-- Chemical Synthesis-- (1976-1989)
10 SYNTHETIC FUELS
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201 -- Chemical & Physicochemical Properties
CARBURIZATION
CATALYSTS
CATALYTIC EFFECTS
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
DATA
DESORPTION
ELEMENTS
EXPERIMENTAL DATA
FISCHER-TROPSCH SYNTHESIS
FLUIDS
GASES
HARDENING
HELIUM
HYDROGEN
INFORMATION
IRON COMPOUNDS
IRON NITRIDES
KINETICS
MASS SPECTROSCOPY
MOESSBAUER EFFECT
NITRIDES
NITROGEN
NITROGEN COMPOUNDS
NONMETALS
NUMERICAL DATA
PNICTIDES
RARE GASES
REACTION KINETICS
RESEARCH PROGRAMS
SPECTROSCOPY
SURFACE HARDENING
SURFACE TREATMENTS
SYNTHESIS
TRANSITION ELEMENT COMPOUNDS