Deactivation by carbon of nickel and nickel-molybdenum methanation catalysts
Deactivation by carbon of nickel and nickel-molybdenum methanation catalysts was studied because the Ni-Mo catalysts were more resistant to sulfur poisoning than nickel in the Bi-Gas process for methanation of coal-derived synthesis gas. The tests included fixed-bed specific rate measurements at 498/sup 0/K, carbon deposition runs at 723/sup 0/K and low pressure (138 kPa) or high pressure (2600 kPa) in a fixed bed, fluidized-bed tests at 723/sup 0/K and 138 kPa, and catalyst regeneration tests in 1-3% air in nitrogen or 1-4% oxygen in nitrogen of a commercial nickel, a commercial nickel-molybdenum, and a commercial nickel-molybdenum-copper catalyst. At low pressure, the resistance to carbon deposition decreased in the order Ni > sulfided Ni > Ni-Mo-Cu > Ni-Mo > presulfided Ni-Mo-Cu. Deactivation at high-pressure, high-conversion conditions was masked by a fast reaction rate in a moving reaction zone which moved downstream, so that gradual deactivation was not observed. Deactivation in the fluidized bed was more rapid than in the fixed bed and the Ni-Mo catalyst deactivated more slowly than the Ni-Mo-Cu catalyst. Presulfiding apparently poisoned the gasification of active carbon. The catalysts were regenerated in dilute air or oxygen, but suffered 18-71% loss of surface area. A deactivation model that correctly described all observed phenomena was developed.
- Research Organization:
- Brigham Young Univ.
- OSTI ID:
- 6189983
- Report Number(s):
- CONF-800303-
- Journal Information:
- Prepr. Pap., Am. Chem. Soc., Div. Fuel Chem.; (United States), Journal Name: Prepr. Pap., Am. Chem. Soc., Div. Fuel Chem.; (United States) Vol. 25:2; ISSN ACFPA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
010404* -- Coal
Lignite
& Peat-- Gasification
090121 -- Hydrocarbon Fuels-- Chemical Synthesis-- (1976-1989)
10 SYNTHETIC FUELS
BI-GAS PROCESS
CARBON
CATALYSTS
CHEMICAL REACTIONS
COAL GASIFICATION
DEACTIVATION
ELEMENTS
FLUIDIZED BED
FOULING
GASIFICATION
MATHEMATICAL MODELS
METALS
METHANATION
MOLYBDENUM
NICKEL
NONMETALS
OPERATION
PACKED BED
POISONING
PRESSURE EFFECTS
REGENERATION
SULFUR
TESTING
THERMOCHEMICAL PROCESSES
TRANSITION ELEMENTS