The Reaction of Oxygen-Nitrogen Mixtures with Granular Activated Carbons Below the Spontaneous Ignition Temperature

摘要

The formation of carbon monoxide and carbon dioxide was followed in the reaction of oxygen-nitrogen mixtures with granular carbons in flow systems. The results may be divided into three categories: (1) In the temperature range 50-200 degrees C, there is anomalous desorption with the formation of a number of maxima in the concentrations of CO and CO2, (2) a higher temperature range in which there is a steady decay of CO and CO2 concentration with first order rate constants observed at constant temperature, and (3) the attainment of a spontaneous ignition temperature (SIT) with good reproducibility. A model is proposed in which a surface carbon-oxygen network of some complexity exists as a barrier to further oxidation. The complex decomposes progressively with increase in temperature with CO and CO2 as end products. When the decomposition of the complex exceeds the rate of formation, the barrier is penetrated and the oxygen can then enter the bulk carbon where unrestricted can take place. This occurs above the SIT. (Author)