2232.     MEDVEDEV, S. S.  [Catalytic Oxidation of Methane to Formaldehyde.  I.]  Trans. Karpov Chem. Inst., No. 3, 1924, pp. 54-65; Chem. Abs., vol. 21, 1927, p. 2457.

        Medvedev experimented with Au, Pt, Mn2O3, NiO, Al2O3, CuO, Ag2O, PbO, and CeO2 catalysts on an asbestos base.  At low rates of flow (1 l. in 20 min.) and at low temperatures (250°-350°) only CO2 is obtained.  Mn2O3 proved to be the most, CuO the least active catalyst.  At temperatures above 500° and a rate of 1 l. per min., traces of HCHO and a little CO appear besides CO2 with CuO as a catalyst, but not with the others.  The Medvedev interprets as evidence of the acceleration of all reactions by the catalysts or their nonspecificity.  Glass at 600° gives a large yield of HCHO, which is attributed to the lesser chemical activity of such a surface in not being able to form peroxides as in the case of metals and their oxides.  With CH4 (containing 3-7% H2) Pb catalysts (borates, phosphates, and their mixtures) gave the highest yields of HCHO at 500°-700°.  The activity of these catalysts, however, was referred to the presence of volatile impurities, as lead chloride, since a long series of experiments showed that small concentrations of HCl (0.13%) in the gases was very beneficial in raising the relative yield of HCHO.  Medvedev’s best results are exceptionally high.  Thus at 600° from a mixture containing 13.8% CH4 and 17.98% O2 with a velocity of 0.23 l. per min., the yield of HCHO was 5.02% of the CH4 taken, 8.65% CH4 being decomposed, that is, 58.04% of the decomposed CH4 decomposed to HCHO.

        MEHL, R. F.  See abs. 3648, 3649.