The effect of pressure on the formation of nitrogen oxides from coal char combustion in a small fixed bed

The evolution of NO, NO₂ and N₂O from the combustion of a lignite char was determined in a fixed-bed reactor as a function of the total pressure, the temperature of the bed, the partial pressure of oxygen and the flow rate of oxygen. The results indicate that an increase in pressure increased the NO₂ formation, while NO and N₂O decreased. The partial pressure of oxygen had a weak effect on NO formation. These results must be interpreted in accordance with the fact that the gases collected represent more closely the desorption step of oxidized-nitrogen-char reactions than those obtained in situations where homogeneous and heterogeneous reactions of nitrogen species are difficult to separate.