Critical condition limits for the high-temperature oxidation of gases on a catalyst particle

The critical conditions have been analytically determined for the high-temperature oxidation of gases over a catalyst. At certain catalyst particle sizes and in a certain range of surrounding gas temperatures, there are gas autoignition and induced ignition regions provided that the reactor walls remain cold. Inside the autoignition region, there can be a catalytic gas autoignition on the particle surface at any initial temperature of the latter. In the induced ignition region, the catalytic combustion of gases occurs at a catalyst temperature above some critical value. The limiting critical concentrations of the combustible component for gas autoignition and induced ignition have been analytically estimated. A gas temperature effect on the limiting critical conditions and on the parameters at which these conditions undergo degeneration has been revealed for catalyst particles with different emissivities. Depending on the catalyst particle size, the upper boundaries of the gas autoignition and induced ignition regions are determined by the effect of radiative heat loss.