Purification of Nitrous Oxide via Thermal Decomposition with the Assistance of Methane: Mechanistic Study of By-Reactions

Abstract

Efficient and economical purification of nitrous oxide (N₂O), one of the most abundant greenhouse gases, is urgently needed to prevent global warming, especially from exhaust emissions produced during adipic acid production. This study investigates the N₂O thermal decomposition process via high-temperature incineration (800–1400 °C), as well as the effects of oxygen (O₂) and methane (CH₄) on deN₂O efficiency and nitrogen selectivity. Under sufficient reaction conditions, deN₂O efficiency reached 100% at ∼1000 °C. The introduction of CH₄ was found to significantly enhance deN₂O efficiency, with the addition of 5% CH₄ resulting in complete N₂O removal at <900 °C. Additionally, the influences of O₂ and CH₄ on the products nitric oxide and nitrogen dioxide (NO₂) were analyzed via temperature-programmed reaction monitoring. Combined with the energy barriers obtained from density functional theory calculations, the reaction pathway network of N₂O decomposition with and without CH₄ was established. Moreover, the reaction rate equation for the crucial byproduct NO₂ was derived from the elementary steps in the reaction network.