A kinetic and experimental analysis of the co-oxidation of ammonia and dimethoxymethane employing SVUV-PIMS

The carbon-neutral potential of ammonia is constrained by fundamental combustion barriers, driving the development of advanced bio-fuel blends as kinetic enhancement strategies. In this research, co-oxidation experiments of NH 3 and dimethoxymethane (DMM, CH 3 OCH 2 OCH 3 ) were executed in a jet-stirred reactor (JSR) under 1 atm and 730–1060 K. Through the use of state-of-the-art synchrotron radiation vacuum ultraviolet photoionization mass spectrometry (SVUV-PIMS) for online diagnostics, we achieved the first quantification of the species pool in the reaction system, covering C/H/O compounds and various key nitrogen-containing intermediates. The experimentally derived species profiles served as the foundation for refining a kinetic model to describe NH 3 and DMM co-oxidation. The model was updated based on experimental and literature data, with key modifications to the rate constants for H-atom abstraction (DMM, NH 3 , intermediates) and the primary N 2 O consumption pathway. Ultimately, the improved model substantially improves the prediction of NH 3 /DMM co-oxidation species distribution (especially for DMM, NH 3 , CH 3 OCHO, CH 2 O, N 2 O, etc.), and it can also accurately reproduce ignition delay times and laminar flame speeds from previous studies. Additionally, the kinetic analysis further clarified the co-oxidation reaction pathways of NH 3 /DMM, especially highlighting the non-negligible influence of some key reaction pathways on their co-oxidation behaviour, such as CH 3 OCH 2 OCH 3 + NH 2 = CH 3 OCH 2 OCH 2 (CH 3 OCHOCH 3 ) + NH 3 , CO + N 2 O = N 2 + CO 2 , etc. This research provides critical experimental data and a more reliable kinetic model, advancing our understanding of the chemical kinetics underlying NH 3 /DMM co-combustion.