Catalytic properties of BaMAl sub 11 O sub 19-. alpha. (M = Cr, Mn, Fe, Co, and Ni) for high-temperature catalytic combustion
- Kyushu Univ., Kasuga, Fukoka (Japan)
Series of cation-substituted barium hexaaluminates, BaMAl{sub 11}O{sub 19-{alpha}}, (M = Cr, Mn, Fe, Co, and Ni), were investigated as catalysts for high-temperature combustion. Cation-substituted barium hexaaluminates showed high sintering resistance and retained a large surface area above 10 m{sup 2}/g even after heating at 1300 C. Transmission electron microscopic observation revealed that anisotropic crystal growth is the reason for the high heat resistance of the hexaaluminate. Manganese-substituted barium hexaaluminate, BaMnAl{sub 11}O{sub 19-{alpha}}, was most active for CH{sub 4} combustion. From temperature-programmed desorption of oxygen and thermogravimetric analysis of oxidation states of substituted cations, it was concluded that the catalytic activity was accelerated by oxygen sorption accompanied by reduction-oxidation of M in the hexaaluminate lattice. Accordingly, the catalytic activity of BaMAl{sub 11}O{sub 19-{alpha}} is approximately regulated by the difference between the heats of formation of sesquioxides of M from monoxide, i.e., ({Delta}H{sub f}{degree}(MO{sub 1.5}) - {Delta}H{sub f}{degree}(MO)), which is minimum at M = Mn. The catalytic activity of the BaMn{sub x}Al{sub 12-x}O{sub 19-{alpha}} system was measured as a function of Mn content. However, the large area and high catalytic activity were obtained only when the amount of Mn was small enough to not destroy the single phase of hexaaluminate. Retention of large surface area is the most prominent feature for high-temperature catalytic combustion.
- OSTI ID:
- 7054833
- Journal Information:
- Journal of Catalysis; (USA), Journal Name: Journal of Catalysis; (USA) Vol. 120:2; ISSN 0021-9517; ISSN JCTLA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400800* -- Combustion
Pyrolysis
& High-Temperature Chemistry
ALKALINE EARTH METAL COMPLEXES
ALKANES
ALUMINATES
ALUMINIUM COMPOUNDS
BARIUM COMPLEXES
CATALYSTS
CATALYTIC COMBUSTORS
CATALYTIC EFFECTS
CHEMICAL ANALYSIS
CHEMICAL REACTIONS
CHROMIUM COMPLEXES
COBALT COMPLEXES
COMBUSTION
COMBUSTORS
COMPLEXES
CONTROL
CRYSTAL GROWTH
DESORPTION
ELECTRON MICROSCOPY
ELEMENTS
FABRICATION
GAS TURBINES
GRAVIMETRIC ANALYSIS
HYDROCARBONS
IRON COMPLEXES
MACHINERY
MANGANESE COMPLEXES
METHANE
MICROSCOPY
NICKEL COMPLEXES
NONMETALS
ORGANIC COMPOUNDS
OXIDATION
OXYGEN
OXYGEN COMPOUNDS
QUANTITATIVE CHEMICAL ANALYSIS
REDUCTION
SINTERING
SURFACE AREA
SURFACE PROPERTIES
TEMPERATURE CONTROL
THERMAL ANALYSIS
THERMAL GRAVIMETRIC ANALYSIS
THERMOCHEMICAL PROCESSES
TRANSITION ELEMENT COMPLEXES
TRANSMISSION ELECTRON MICROSCOPY
TURBINES
TURBOMACHINERY
VERY HIGH TEMPERATURE