Advancements in Nitrous Oxide Abatement: A Review of Direct Catalytic Decomposition and Selective Catalytic Reduction

Abstract

Nitrous oxide (N₂O) emissions pose significant environmental and regulatory challenges, which necessitates a need for advancements in catalytic abatement methods. This review evaluates catalytic systems with insights for industrial applications, covering three catalyst types: supported metal catalysts (Rh/CeO₂, Ru/γ-Al₂O₃, Rh/Al₂O₃, and Pd/Al₂O₃), transition metal oxides (Co₃O₄, Mn₂O₃, CuO, and NiO), and ion-exchanged zeolites (Fe-, Co-, and Cu- on ZSM-5, BEA, SSZ-13, FER, and MOR). For direct decomposition reactions, the catalytic performance is influenced by the redox and oxygen desorption properties, as well as by the inclusion of promoters. For SCR applications, iron-based zeolites (e.g., Fe-MFI, Fe-MOR, Fe-BEA, and Fe-SSZ-13) offer high activity, low cost, and low toxicity. Among the reductants, CO and hydrocarbons demonstrate superior efficiency when compared to H₂ and NH₃ for Fe-BEA zeolites. The presence of O₂ and H₂O was shown to inhibit both reaction pathways, while SO₂ can cause irreversible deactivation. For SCR, NO demonstrates competitive adsorption, which inhibits the reaction with CO and hydrocarbon reductants. Additionally, transient kinetic studies and density functional theory were highlighted in how they inform reaction mechanisms. Furthermore, high-throughput experimentation and machine learning can be leveraged to overcome the current and future industrial shortcomings of N₂O abatement processes.