706.    ---------------.  [DOEHLEMANN, E.]  [Mechanism of the Water-Gas Reaction on an Iron Catalyst.]  Ztschr. Elektrochem., vol. 44, 1938, pp. 178-183; Chem. Abs., vol. 32, 1938, p. 4060.

     Velocity of the reaction CO₂+H₂→CO+H₂O on an Fe-foil catalyst at 910° is essentially proportional to the CO₂ pressure and increases with H₂ pressure somewhat more slowly than corresponds to a direct proportionality.  The stationary C concentration of the Fe catalyst in a water-gas mixture, which is reacting in the direction CO₂+H₂→CO+H₂O, is greater than corresponds to the equilibrium : C (dissolved in γ-Fe)+CO₂ (gas)=2 CO (gas).  This qualitative result agrees with the working hypothesis that the catalytic water-gas reaction can be explained as a transfer of an O atom from CO₂ to H₂ through the formation of adsorbed O on Fe as an intermediate product; thus, (1) formation of O (adsorbed) as a relatively slow reaction: CO₂ (gas)=CO (gas) +O (ads):  It is followed by (2) a rapid reaction (practically at equilibrium); O (ads)+H₂(gas)=H₂O(gas):  Then (3) a rapid reaction of C dissolved in Fe; C (dissolved in γ-Fe)+O(ads)=CO(gas).  The data obtained did not confirm this mechanism quantitatively, probably because of simultaneous reactions.

     DOHERTY, H. G.  See abs. 3154.