Summary
A general picture of the mechanism of oxidative methane coupling over metal oxides has been proposed on the basis of kinetic and CH4-CD4 exchange studies on Sm2O3. The rate-determining step is the hydrogen abstraction from the methane activated on the surface. A diatomic oxygen species, probably O2 2−, is responsible for the abstraction of hydrogen. This active oxygen must be in equilibrium with the gaseous oxygen. Lattice oxygen atoms do not contribute to the oxidative coupling reaction. The main products in the ethanes formed in the reaction of the mixture of CH4, CD4, and O2 were CH3CH3, CH3CD3, and CD3CD3, indicating that the CH3. radical in the gas phase or the CH3 group on the surface is the reaction intermediate.
Calcination of the NiO added with LiNO3, Li(OH), or Li2CO3 at > 973 K generates a Li and NiO solid solution LixNi1−xO. The oxidative coupling of methane over this oxide is quite unusual. Lattice oxygen atoms of the oxide are responsible for the activation of methane. The rate of formation of C2 products depends on the square of methane pressure. The rate-determining reaction is the coupling step of the methyl groups adsorbed on Ni3+—O2− pair sites. The addition of LiCI to NiO, however, did not produce a compound oxide between Li and NiO. The reaction over this LiCl-added NiO can be explained in terms of the same reaction mechanism proposed for the reaction over Sm2O3.
Another example of the important role of lattice oxygen was observed for the partial oxidation of methane into formaldehyde over the mixed oxide of Fe, Nb, and B. The oxygen isotope analysis of the products from CH4 and 18O2 has indicated that the bulk oxygen of this oxide is preferentially incorporated into the products (HCHO, CO, CO2, and H2O).
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References
Asami, K., T. Shikada, K. Fujimoto, and H. Tominaga. 1987. Oxidative coupling of methane over lead oxide catalyst: Kinetic study and reaction mechanism. Ind. Eng. Chem. Res. 26: 2348–53.
Baerns, M., J.R.H. Ross, and K. van der Wiele. 1988. Methane Activation. Amsterdam: Elsevier Science Publishers. (Catal. Today 4:271–494.)
Cant, N.W., C.A. Lukey, P.F. Nelson, and R.J. Tyler. 1988. The rate controlling step in the oxidative coupling of methane over a lithium-promoted magnesium oxide catalyst. J. Chem. Soc. Chem. Commun. 766–8.
Driscoll, D.J., W. Martir, J.-X. Wang, and J.H. Lunsford. 1985. Formation of gas-phase methyl radicals over MgO. J. Am. Chem. Soc. 107: 58–63.
Gesser, H.D., N.R. Hunter, and C.B. Prakash. 1985. The direct conversion of methane to methanol by controlled oxidation. Chem. Rev. 85: 235–44.
Hatano, M., and K. Otsuka. 1988. Alkali metal-doped transition metal oxides active for oxidative coupling of methane. Inorg. Chim. Acta 146: 243–7.
Hatano, M., and K. Otsuka, 1989. The oxidative coupling of methane on lithium nickelate(III). J. Chem. Soc. , Faraday Trans. 1 85: 199–206.
Hutchings, G.J., M.S. Scurrell, and J.R. Woodhouse. 1987. The role of surface 0-in the selective oxidation of methane. J. Chem. Soc. , Chem. Commun. 1388–9.
Hutchings, G.J., M.S. Scurrell, and J.R. Woodhouse. 1989. Oxidative coupling of methane using oxide catalyst. Chem. Soc. Rev. 18: 251–83.
Ito, T., J.-X. Wang, C.-H. Lin, and J.H. Lunsford. 1985. Oxidative dimerization of methane over a lithium-promoted magnesium oxide catalyst. J. Am. Chem. Soc. 107: 5062–8.
Jones, C.A., J.J. Leonard, and J.A. Sofranko. 1987a. The oxidative conversion of methane to higher hydrocarbons over alkali-promoted Mn/SiO2. J. Catal. 103: 311–19.
Jones, C.A., J.J. Leonard, and J.A. Sofranko. 1987b. Fuels for the future: Remote gas conversion. Energy and Fuels 1: 12–16.
Keller, G.E., and M.M. Bhasin. 1982. Synthesis of ethylene via oxidative coupling of methane. J. Catal. 73: 9–19.
Keulks, G.W., L.D. Krenzke, and T.M. Notermann. 1978. Selective oxidation of propylene. Adv. Catal. 27: 183–225.
Komatsu, T., T. Amaya, and K. Otsuka. 1989. LiC1 doped cobalt oxide is an active catalyst for the formation of ethylene in the oxidative coupling of methane. Catal. Leu. 3: 317–22.
Lee, J.S., and S.T. Oyama. 1988. Oxidative coupling of methane to higher hydrocarbons. Catal. Reu.-Sci. Eng. 30: 249–80.
Lin, C.-H., K.D. Campbell, J.-X. Wang, and J.H. Lunsford. 1986. Oxidative dimerization of methane over lanthanum oxide. J. Phys. Chem. 90: 534–7.
Liu, R.-S., M. Iwamoto, and J.H. Lunsford. 1982. Partial oxidation of methane by nitrous oxide over molybdenum oxide. J. Chem. Soc. , Chem. Commun. 78–9.
Naccache, C. 1971. ESR study of species formed by reaction of O- adsorbed on magnesium oxide with O2, CO and ethylene. Chem. Phys. Lett. 11: 323–5.
Nelson, P.F., C.A. Lukey, and N.W. Cant. 1989. Measurements of kinetic isotope effects and hydrogen/deuterium distributions over methane oxidative coupling catalysts. J. Catal. 120: 216–30.
Otsuka, K. 1987. Direct conversion of methane to higher hydrocarbons. Sekiyu Gakkaishi 30: 385–96.
Otsuka, K., M. Hatano, and T. Komatsu. 1989. Synthesis of C2H4 by partial oxidation of CH4 over LiCI/NiO. Catal. Today 4: 409–19.
Otsuka, K., M. Inaida, Y. Wada, T. Komatsu, and A. Morikawa. 1989. Isotopic studies on oxidative methane coupling over samarium oxide. Chem. Lett. 1531–4.
Otsuka, K., and K. Jinno. 1986. Kinetic studies on partial oxidation of methane over samarium oxides. Inorg. Chim. Acta 121: 237–41.
Otsuka, K., K. Jinno, and A. Morikawa. 1986. Active and selective catalysts for the synthesis of C2H4 and C2H6 via oxidative coupling of methane. J. Catal. 100: 353–9.
Otsuka, K., T. Komatsu, K. Jinno, Y. Uragami, and A. Morikawa. 1988. Activation of methane and synthesis of formaldehyde by partial oxidation. In Proceedings of the 9th International Congress on Catalysis, Vol. 2, ed. M.J. Phillips and M. Ternan, pp. 915–22. Ottawa: The Chemical Institute of Canada.
Otsuka, K., Q. Liu, and A. Morikawa. 1986. Active and selective catalysts in oxidative coupling of methane. Nickel oxides with salts of alkali metals. Inorg. Chim. Acta 118: L23–4.
Otsuka, K., Y. Murakami, Y. Wada, A.A. Said, and A. Morikawa. 1990. Oxidative coupling of methane, ethane, and propane with sodium peroxide at low temperatures. J. Catal. 121: 122–30.
Otsuka, K., and T. Nakajima. 1987. Oxidative coupling of methane over samarium oxides using N2O as the oxidant. J. Chem. Soc., Faraday Trans. 1 83: 1315–21.
Otsuka, K., A.A. Said, K. Jinno, and T. Komatsu. 1987. Peroxide anions as possible active species in oxidative coupling of methane. Chem. Lett. 77–80.
Otsuka, K., Y. Shimizu, and T. Komatsu. 1987. Ba doped cerium oxides active for oxidative coupling of methane. Chem. Lett. 1835–8.
Pitchai, R., and K. Klier. 1986. Partial oxidation of methane. Catal. Rev.—Sci. Eng. 28: 13–88.
Zhen, K.J., M.M. Khan, C.H. Mak, K.B. Lewis, and G.A. Somorjai. 1985. Partial oxidation of methane by nitrous oxide over molybdenum oxide. J. Catal. 94: 501–7.
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Otsuka, K., Hatano, M. (1992). Partial Oxidation of Methane over Metal Oxides: Reaction Mechanism and Active Oxygen Species. In: Wolf, E.E. (eds) Methane Conversion by Oxidative Processes. Van Nostrand Reinhold Catalysis Series. Springer, Dordrecht. https://doi.org/10.1007/978-94-015-7449-5_3
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DOI: https://doi.org/10.1007/978-94-015-7449-5_3
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