3642a.     WEITKAMP, A. W., AND FRYE, C. G.  Products of the Hydrogenation of Carbon Monoxide Over an Iron Catalyst.  Relation of Product Composition to Reaction Mechanism.  Am. Chem. Soc., 121st Meeting abs., March-April 1952, p. 11-M.

        Evaluation of proposed reaction mechanisms for the hydrocarbon synthesis process was prompted by the availability of new product composition data and a knowledge of the effects of certain operating variables on product composition.  The hydrocarbon synthesis process consists of several competing and concurrent reactions.  The chemical steps in the formation of primary-product molecules are initiation, chain extension, and termination.  The initiator of chain growth may be adsorbed radical, possibly formed by hydrogenation on surface carbide.  The adsorbed radical is enlarged by repeated addition and hydrogenation of adsorbed CO molecules.  The termination reaction produces mainly alcohols or aldehydes and olefins.  Competition between growth and termination is responsible for the exponential decrease in yields of successive C-number fractions.  Distributions of normal and branched isomers are explained on the assumption of a statistical distribution of growth on the 2 C atoms last added to the adsorbed radicals.  Secondary reactions convert part of the original olefins to paraffins and may convert part of the alcohols or aldehydes to acids and ketones.