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Platinum Metals Rev., 1998, 42, (3), 98

Direct Methane Oxidation by Platinum Catalyst


The conversion of natural gases into more useful alcohols is usually achieved by changing the alkane component of the natural gas into a combination of carbon monoxide and hydrogen (synthesis gas) which is then converted into higher order alkanes by the Fischer-Tropsch reaction (1). These processes require a lot of energy, so it would be less costly if the alkane component, usually methane, could be directly converted into alcohols, by selective oxidation; the main difficulty being the low reactivity of the C-H bond. One such method, from Catalytica Advanced Technologies Inc., California, used toxic mercury(II) salts, and resulted in methane being converted into a methanol ester in an approximately 43 per cent yield.

Now, however, the same group has reported the development of a successful, stable platinum catalyst (2). Platinum salts were already known to be more efficient for the oxidation of methane in strong oxidising acids, but were not stable in hot (>100°C) acid. By utilising stabilising ligands, catalysts of greater stability were developed. They found that the addition of a bidiazine ligand to a platinum(II) salt gave high stability to strong acids and oxidising conditions. One of the most effective catalysts was dichloro(η-2-{2,2′-bipyrimidyl})platinum(II), [(bpym)PtCl2]. Three key steps were proposed for the conversion of methane: C-H activation, oxidation and functionalisation.

The present reaction, which takes place at 220°C, converts ∼ 72 per cent of the methane to methyl bisulfate, and is thought to proceed via the formation of a methyl-platinum species. The authors state that the mechanism of the C-H reaction needs more investigation as the factors controlling its reactivity could lead to greater control of the reaction selectivity.



  1. 1
    R. C. Everson, and D. T. Thompson,, Platinum Metals Rev ., 1981, 25, ( 2 ), 50 ; F. King,, E. Shutt and A. I. Thompson, op. cit ., 1985, 29, ( 4 ), 14
  2. 2
    R. A. Periana,, D. J. Taube,, S. Gamble,, H. Taube,, T. Satoh and H. Fujii, Science, 1998, 280, ( 5363 ), 560

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