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 Po/2 P1-Po, 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 1st, 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.