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.
