The Behavior of Catalytic, Low-Temperature N2O Decomposition (LT-deN2O) in the Presence of Sulfur-Containing Compounds on Nitric Acid Plants

The production of nitric acid represents the primary source of nitrous oxide (N2O) emissions. During pilot-scale studies of N2O reduction on a low-temperature catalyst on nitric acid plants, it was observed that increasing the concentration of NH3 resulted in a decrease in the degree of N2O decomposition. This suggested that N2O was formed by the oxidation of NH3. Measurements at different temperatures, conducted after the N2O reduction trials, resulted in the N2O concentration at the inlet equal to the concentration at the outlet, indicating catalyst deactivation. To identify the causes of deactivation, the physicochemical properties of the catalyst were investigated. XRF analysis revealed the presence of sulfur. The results suggest the necessity of removing sulfur from the raw gas before the reduction of N2O on the low-temperature catalyst in practical applications.