On Oxidation of Ammonia and Diethoxymethane

Ammonia (NH3), as a renewable energy carrier, demonstrates significant potential for internal combustion engine applications. However, challenges such as its poor combustion performance and nitrogen oxide (NOx) emissions remain unresolved. The introduction of biomass-derived oxygenated fuel diethoxymethane (DEM) effectively enhances reactivity and achieves full life-cycle carbon neutrality. This study aims to investigate the synergistic oxidation mechanisms and reaction kinetics of NH3/DEM-blended fuels. Synchrotron vacuum ultraviolet photoionization mass spectrometry (SVUV-PIMS) was employed to systematically examine the oxidation characteristics of NH3/DEM mixtures at atmospheric pressure over the temperature range of 710–1110 K. A total of 17 key intermediates and stable products were identified, including NO, NO2, C2H4, CH2O, CH3CHO, C2H5OCHO, CH3NO2, and C2H5NO2. A newly developed kinetic model comprising 778 species and 4273 elementary reactions was constructed, which accurately predicts the compositional evolution of the fuel blends and has been validated against ignition delay times and laminar flame speeds of pure fuels. This model elucidates the dominant reaction network of ammonia and DEM co-oxidation, the formation pathways of carbon–nitrogen species, and the mechanisms of NOx formation in the cocombustion system. This work provides the first mechanistic insights into NH3/DEM cocombustion, contributing fundamental knowledge to support the sustainable development of ammonia-based fuels.