Simulation-Guided Optimization of NH ₃ /H ₂ Cocombustion over a CuO Catalyst: Achieving High-Efficiency and near-Zero NO x Emissions

Ammonia (NH 3 ) is a promising carbon-free fuel, but its industrial application is challenged by low reactivity and substantial nitrogen oxide (NO x ) emissions. This study proposes a simulation-guided reactant optimization strategy to achieve high-efficiency NH 3 combustion with exceptional nitrogen (N 2 ) selectivity. Chemical kinetic modeling using Chemkin-Pro elucidated intrinsic mechanistic bottlenecks: while hydrogen (H 2 ) acts as a promoter, excessive H 2 functions as a radical scavenger by preferentially consuming OH radicals, whereas excess oxygen (O 2 ) accelerates the deep oxidation of amine intermediates toward NO x . Guided by these mechanistic insights, we experimentally validated this strategy over a CuO catalyst, where surface reactions closely mirrored gas-phase radical trends. Specifically, H 2 functioned as a critical chemical promoter, generating surface-active species that triggered low-temperature ignition. Furthermore, the catalyst exhibited robust activity under O 2 -lean conditions (X O2 = 0.7), likely due to the rapid saturation of surface active sites, effectively suppressing deep oxidation pathways without sacrificing reactivity. Under the optimized conditions (X H2 = 3 and X O2 = 0.7), the CuO system achieved complete NH 3 conversion at 500 °C with > 99% N 2 selectivity at 600 °C. These results demonstrate that synergistically coupling radical-controlled fuel composition with selective catalytic oxidation provides a robust pathway for developing eco-friendly NH 3 power systems.