The explosive oxidation of carbon monoxide at lower pressures

Abstract

The oxidation of carbon monoxide may occur either directly or by an indirect reaction with steam. Under appropriate conditions the oxidation takes place at a measurable rate, and there are also two distinct types of explosive reaction. The indirect oxidation in presence of steam takes place with measurable speed in the range 550°-600°C., and appears to involve reaction chains analogous to those occurring in the combination of hydrogen and oxygen. The direct oxidation requires a considerably higher temperature: in a silica vessel, for example, there is a slow surface reaction at about 700°C. This has been shown to be independent of residual traces of moisture, the kinetics being fundamentally different from those of the indirect oxidation. The direct oxidation can also be brought about by sparking dry mixtures of carbon monoxide and oxygen at high pressures. Bone and Weston have shown that the spectrum emitted by the exploding gases is quite different from that given by the flame of moist carbon monoxide; thus the mechanism of the “dry” reaction is really an independent one. Moreover, Garner has shown that there is an abrupt change in the nature of the radiation emitted by a carbon monoxide flame when a small amount of hydrogen is added, this, again, confirms the existence of two separate mechanisms of oxidation.