Characterization of Bismuth-manganese Oxide Catalysts for Methane Oxidative Coupling
(1992) Applied Catalysis A: General — Vol. 89, n° 2, p. 169-182 (1992)
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- Abstract
- This paper reports a finding, namely a cooperation between separate phases, which may help understand the mechanism of oxidative coupling of methane. The activity of co-precipitated bismuth-manganese oxides in the oxidative coupling of methane, measured in the continuous flow regime, is maximum for Bi:Mn = 1:2. The catalysts have been investigated by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy and microanalysis; catalytic pulse experiments were performed. The Bi2Mn4O10 phase is present in these catalysts. But, surprisingly, although it corresponds to the Bi:Mn ratio of 1:2 giving maximum activity, it decomposes to alpha-Bi2O3 and alpha-Mn2O3 in a few hours during the catalytic test. The higher catalytic activity observed at Bi:Mn = 1:2 thus does not seem due to the Bi2Mn4O10 phase. The high activity catalyst is actually composed of Bi2O3 in contact with an other phase. This might be a Bi-depleted Bi2Mn4O10-like phase; it is speculated that this phase could donate oxygen to Bi2O3 and make it more active. This would suggest that oxygen mobility or spill-over between phases. observed to be beneficial in other reactions occurring at 350-450-degrees-C, also promotes the selective oxidative coupling of methane above 700-degrees-C.
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Baidikova, I., Delmon, B., Matralis, H., Naud, J., Papadopoulou, C., & Mamedov, EA. (1992). Characterization of Bismuth-manganese Oxide Catalysts for Methane Oxidative Coupling. Applied Catalysis A: General, 89(2), 169-182. https://doi.org/10.1016/0926-860X(92)80231-Z (Original work published 1992)