The oxidation of carbon monoxide

Abstract

Although the reaction between carbon monoxide and oxygen has long been the subject of experimental study, the mechanism of the process is far from being completely understood. Most of the earlier investigations of Dixon and others were concerned with the initiation and propagation of flame or detonation waves in mixtures of the two gases, and showed especially the important part which water plays in the reaction. More recently experiments have been made in different laboratories on the kinetics of the slow reaction occurring below the ignition temperature. From the results of these it should be easier to draw conclusions about the mechanism of the change than it is from experiments on the explosive combination, but on account of the differences in the conditions under which the various investigations have been made, and, to some extent, of the divergences in the results themselves, it is still difficult to correlate all the available information and form a coherent theory of the oxidation. The lack of uniformity in some of the previous work may be attributed partly to variation in water content of the gases used, for, as the experiments of Bone and Weston have shown, the catalytic oxidation in presence of water and the direct combination are probably distinct and independent processes. It seemed of interest therefore to examine the problem further, investigating under more strictly comparable conditions the influence on the rate of the slow reaction of various factors such as vessel size, and concentrations, in particular that of water. With this knowledge about the kinetics of the “wet” reaction it was proposed to proceed to the study of the reaction which can be made to take place at higher temperatures between the carefully dried gases. If the “dry” reaction is determined, as some have thought, by the residual traces of moisture, the kinetics must remain essentially the same as in the “wet” reaction. They appear in fact to be entirely different. This shows once more that the direct oxidation of dry carbon monoxide is possible.