Formation of NOx and N₂O Through Oxidation of NH₃ and HCN Catalyzed by Limestone

Abstract

Catalytic effects of limestone on oxidation of NH3 and HCN were investigated with a quartz fixed bed reactor at temperatures between 923K and 1123K. Limestone was found to be an active catalyst of oxidation of NH₃ and HCN. The major product of NH₃ oxidation was NO.N₂O was not detected as a product of NH₃ oxidation. The intrinsic selectivity of NH₃ to N₂O was calulated by eliminating the effect of secondary decomposition of N₂O by coexisting limestone. The intrinsic selectivity of NH₃ to N₂O was no higher than 3%. The major products of HCN oxidation were NO and N₂. Selectivity of HCN to N2O for catalytic oxidation was 3 to 10%, which are considerably lower than the reported value of selectivity for homogeneous HCN oxidation.