3215.     SMITH, D. F., HAWK, C. O., AND GOLDEN, P. L.  Mechanism of the Formation of Higher Hydrocarbons From Water Gas.  Jour. Am. Chem. Soc., vol. 52, 1930, pp. 3221-3232; Chem. Abs., vol. 24, 1930, p. 4755.

        Experiments are reported that show that cracking of the heavier hydrocarbons does not play any considerable part in the formation of the mixture of hydrocarbons higher than CH₄ when the synthesis is carried out on a Co-Cu-Mn oxide catalyst under the conditions described.  The experiments in which Me₂CO was passed over the catalyst with H₂, N₂, or CO indicate that Me₂CO likewise is not a predominating intermediate.  Me₂CO is almost never present in the products from water gas alone.  Polymerization of C₂H₄ or of higher olefins does not occur.  C₂H₄, at least in concentrations over 10%, enters into reaction upon the Co-Cu-Mn oxide catalyst in the presence of water gas, forming higher hydrocarbons and large quantities of O-containing compounds.  The O-containing compounds dehydrate to a greater or less extent, producing hydrocarbons.  The dehydration is accompanied by some polymerization.  The extent to which C₂H₄ enters into these reactions does not change largely with the C₂H₄ concentration when this is above about 10%, but formation of these intermediate products depends quite markedly upon the concentration of water gas.  The mechanism forming hydrocarbons may be regarded as follows:  There is some association of H₂ and CO on the catalyst surface.  This complex may either decompose, giving an olefin and H₂O, or C₂H₄ or other olefin may combine with it to form an O-containing compound, which may either pass into the products or eliminate H₂O to form a higher olefin hydrocarbon.  The olefins are to be regarded as the primary hydrocarbon products.  They may later be hydrogenated to form paraffin hydrocarbons or pass on into the products, depending upon the experimental conditions of H₂ concentration, space velocity, catalyst, and temperature.  The mechanism of H₂ formation on an Fe-Cu catalyst is essentially different from that on a Co-Cu-Mn oxide catalyst, aside from the relative amounts of CO₂ and H₂O formed, since in this case C₂H₄ does not enter into reaction.

        SMITH, D. F., HAWK, C. O., AND REYNOLDS, D. A.  Synthesis of Higher Hydrocarbons From Water Gas.  II.  See abs. 3214.