3141.     SCHWAB, G. M., AND NAICKER, K.  [Water-Gas Reaction on a Platinum Surface at Low Pressures.]  Ztschr. Elektrochem., vol. 42, 1936, pp. 670-673; Chem. Abs., vol. 30, 1936, p. 7979.

        Kinetics of the reaction H₂+CO₂=CO+H₂O have been studied on a Pt filament 700°-1,200° and at pressures up to 0.3 mm.  By use of H₂SO₄ for removing the H₂O formed, the authors found the rate was independent of the partial pressure of CO₂ and was a complicated function of the partial pressure of H₂ and CO.  The reaction was autocatalytic in the absence, but not in the presence, of an initial partial pressure of CO.  If P₂O₃ was used to remove the H₂O formed, the time of half conversion was proportional to the pressure; the rate was independent of the H₂ pressure.  No auto-catalysis but marked inhibition by CO was observed.  If a cold bath (-90°) was placed around the reaction vessel to remove the H₂O formed, the character of the reaction changed completely.  No reaction occurred below 730°; above 800° the rate was very high and independent of temperature.  The observed rate was 10^-4, which would be calculated by assuming the surface to be covered with adsorbed H and that a reaction occurred every time a CO₂ molecule struck the surface.  The results are interpreted as indicating the existence of enough active points to cover 10^-4 of the surface and points active enough to permit the reaction to occur with no energy of activation.