Modeling study of homogeneous NO and N₂O formation from oxidation of HCN in a flow reactor

To investigate the reaction chemistry of HCN oxidation, a modeling study was performed. The plug flow calculation code was used at atmospheric pressure in the temperature range from 1000 to 1400 K. The effect of initial H ₂O concentrations and that of other components were discussed. The oxidation of HCN is controlled primarily by the HCN + OH reaction in case of increasing H₂O concentration. The oxidation of HCN starts at lower temperatures and the conversion of HCN to NO is inhibited by increase in H ₂O concentration. N₂O formation by the NCO + NO reaction is inhibited by increase in H₂O concentration because of the small amount of NO and NCO. In the presence of initial NO, NCO acts as a reducing agent for NO. NCO mainly reacts with initial NO, so N₂O formation is not affected by H₂O concentration. In case of adding CO, CO oxidation chemistry acts as a source of a radical pool, and HCN oxidation shifts to lower temperatures. Increasing H₂O affects, the consumption of O radical and inhibits NO formation. The effect of H₂O concentration on N ₂O formation is small because of the number of O and H radicals formed by CO oxidation.