Carbon deposition and activity changes over FeRu alloys during Fischer-Tropsch synthesis
The interaction of 3H/sub 2//CO at 1 atm and 573 to 673/sup 0/K with unsupported Ru, Fe, and RuFe alloy powders was investigated using x-ray photoelectron spectroscopy (XPS), secondary ion mass spectrometry (SIMS), and differential chemical kinetics. Direct surface analysis of fresh, reacted, and regenerated surfaces, without exposure to air, shows a strong dependence of carbon deposition on catalyst composition. Pure Ru and Ru doped with 3 atom% Fe show no carbon buildup, and therefore exhibit steady specific activity and selectivity in Fischer-Tropsch synthesis as a function of time on stream. Increasing the iron content of the alloys results in a thick carbon overlayer being deposited during the first few hours of reaction. The carbon overlayer reduces specific activity by a factor of 2 to 3 and shifts selectivity toward lower-molecular-weight products. Regeneration of these catalysts requires heating in H/sub 2/ at 683/sup 0/K. Both XPS and SIMS confirm that pure iron first incorporates carbon into the bulk with a resulting temporary increase in activity and selectivity to saturated products. Selectivity then shifts to lighter products as carbon gradually builds up on the iron carbide surface.
- Research Organization:
- Purdue Univ., West Lafayette, IN
- OSTI ID:
- 6580746
- Journal Information:
- J. Catal.; (United States), Vol. 65:2
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CARBON
DEPOSITION
CARBON MONOXIDE
METHANATION
FISCHER-TROPSCH SYNTHESIS
CATALYSTS
CHEMICAL REACTION KINETICS
HYDROCARBONS
HYDROGEN
CHEMICAL REACTIONS
IRON
CATALYTIC EFFECTS
IRON ALLOYS
RUTHENIUM
RUTHENIUM ALLOYS
EXPERIMENTAL DATA
GRAPHS
TABLES
ALLOYS
CARBON COMPOUNDS
CARBON OXIDES
CHALCOGENIDES
DATA
ELEMENTS
INFORMATION
KINETICS
METALS
NONMETALS
NUMERICAL DATA
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PLATINUM METAL ALLOYS
PLATINUM METALS
REACTION KINETICS
REFRACTORY METALS
TRANSITION ELEMENTS
090121* - Hydrocarbon Fuels- Chemical Synthesis- (1976-1989)