Catalytic activity and deactivation mechanisms of supported NiO in CH/sub 4/ oxidation
The partial oxidation of CH/sub 4/ was studied using a commercial Ni/..cap alpha..-Al/sub 2/O/sub 3/ catalyst. The results show that two operating regimes can be maintained: a low-conversion regime where CO/sub 2/ and H/sub 2/O are formed and a high-conversion regime where CO, CO/sub 2/, H/sub 2/ and H/sub 2/O are formed. The latter regime is established by catalytic light-off which among other conditions depends on temperature, feed composition and catalyst activity. Prior to light-off, the catalyst is in the NiO form. Following light-off, the catalyst is in NiO form near the inlet and metallic form further downstream. A series of NiO/..cap alpha..-Al/sub 2/O/sub 3/ and NiO/ZrO/sub 2/ catalysts were prepared by impregnation and calcination in air between 750 and 1050/sup 0/C. These catalysts were characterized by the BET method, O/sub 2/ chemisorption, x-ray diffraction, electron microscopy and ESCA. Test analyses indicate that the supported NiO particles are made up of a large number of small crystallites which become more dispersed after reduction and reunite after oxidation. The activity of these catalysts for CH/sub 4/ oxidation under pre-light-off conditions was found to decrease dramatically with increasing calcination temperature. However, the calcined catalysts can be reactivated by reduction in H/sub 2/ prior to reaction. The change in activity is attributed mainly to the change in specific activity of NiO which is explained in terms of the change in excess oxygen content.
- OSTI ID:
- 5375151
- Country of Publication:
- United States
- Language:
- English
Similar Records
Surface structure and mechanisms of gasification catalyst deactivation. Quarterly report, May--July 1977
Catalytic and Physical Properties Study on NiO and Pr{sub 2}O{sub 3}-NiO Based Catalyst for CO{sub 2}/H{sub 2} Methanation
Related Subjects
080109* -- Hydrogen-- Production-- Partial Oxidation Processes
090110 -- Hydrocarbon Fuels-- Properties-- (1979-1989)
10 SYNTHETIC FUELS
ALKANES
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON MONOXIDE
CARBON OXIDES
CATALYSIS
CATALYSTS
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL REACTIONS
DEACTIVATION
HYDROCARBONS
HYDROGEN COMPOUNDS
HYDROGEN PRODUCTION
METHANE
NICKEL COMPOUNDS
NICKEL OXIDES
ORGANIC COMPOUNDS
OXIDATION
OXIDES
OXYGEN COMPOUNDS
PARTIAL OXIDATION PROCESSES
THERMOCHEMICAL PROCESSES
TRANSITION ELEMENT COMPOUNDS
WATER
ZIRCONIUM COMPOUNDS
ZIRCONIUM OXIDES