Catalytic decomposition converts N₂O directly to N₂ and O₂ — a thermodynamically favorable but kinetically hindered reaction. Developing efficient catalysts for this transformation is a key green chemistry challenge, applicable both to industrial N₂O abatement and to using N₂O as a mild oxidant in synthesis.
Thermodynamics and Kinetics
The decomposition reaction N₂O → N₂ + ½O₂ is exothermic (ΔH = −82.0 kJ/mol) and spontaneous at all temperatures (ΔG negative above approximately −93°C). However, the homogeneous uncatalyzed reaction is negligibly slow at temperatures below 600°C.
2N₂O → 2N₂ + O₂ ΔH = −164 kJ/mol
Catalyst Systems
Iron-exchanged zeolites (Fe-ZSM-5, Fe-Beta) are among the most active and selective catalysts, capable of operating at 300–500°C. Perovskite-type oxides (LaCoO₃, LaMnO₃) offer good activity at 250–400°C. Rhodium and ruthenium catalysts on oxide supports are active below 200°C.