3222.     SMITS, A., AND WOLFF, L. K.  [Velocity of Transformation of Carbon Monoxide.  I.]  Proc. “Koninkl. Akad. Wetenschappen Amsterdam”, vol. 5, 1903, pp. 417-424; Jour. Chem. Soc., vol. 83, II, 1903, p. 276; Jour. physik. Chem., vol. 35, 1903, pp. 199-215.

        From a study of the catalytic action of Fe, Ni, and Co on the system 2CO=CO₂+C, Boudouard found that at 1,000°, CO₂ in contact with C is almost wholly converted into CO, while, at 445°, the reverse is true.  The authors examine the conditions of the action below 445° when CO is in a metastable condition.  The catalyst was finely divided Ni reduced at 445°.  Observations made at 256°, 310°, and 340° indicated that the action was unimolecular.  The reaction constants, calculated from K=1/t log P_o/2 P₁-P_o, were determined at the above temperatures, the values being 0.000279, 0.00186, and 0.00527, respectively.  During these measurements the activity of the catalyst had not decreased.  The 2 following hypotheses are adduced for the mechanism of the reaction:  First (1) CO₂=CO+O (with measurable velocity), (2) CO+O=CO₂ (with immeasurable velocity; secondly, (1) CO+Ni=C+NiO, (2) CO+NiO=CO₂+Ni.  In the latter case, the 2d stage takes place more quickly than the 1^st, but it need not be assumed that the velocity of one of the stages is immeasurable.  The catalyst was actually Ni and not the C with which it was mixed.