Simulation-Guided Optimization of NH3/H2 Cocombustion over a CuO Catalyst: Achieving High-Efficiency and near-Zero NOx Emissions.

Ammonia (NH3) is a promising carbon-free fuel, but its industrial application is challenged by low reactivity and substantial nitrogen oxide (NOx) emissions. This study proposes a simulation-guided reactant optimization strategy to achieve high-efficiency NH3 combustion with exceptional nitrogen (N2) selectivity. Chemical kinetic modeling using Chemkin-Pro elucidated intrinsic mechanistic bottlenecks: while hydrogen (H2) acts as a promoter, excessive H2 functions as a radical scavenger by preferentially consuming OH radicals, whereas excess oxygen (O2) accelerates the deep oxidation of amine intermediates toward NOx. Guided by these mechanistic insights, we experimentally validated this strategy over a CuO catalyst, where surface reactions closely mirrored gas-phase radical trends. Specifically, H2 functioned as a critical chemical promoter, generating surface-active species that triggered low-temperature ignition. Furthermore, the catalyst exhibited robust activity under O2-lean conditions (XO2 = 0.7), likely due to the rapid saturation of surface active sites, effectively suppressing deep oxidation pathways without sacrificing reactivity. Under the optimized conditions (XH2 = 3 and XO2 = 0.7), the CuO system achieved complete NH3 conversion at 500 °C with > 99% N2 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 NH3 power systems.