Study on the Kinetic Characteristics of NO ₂ with 2-Ethylfuran: N-Atom vs. O-Atom Attack

Exhaust gas recirculation (EGR) technology creates opportunities for chemical interactions between transportation fuels and NO x . In this study, 2-ethylfuran (2EF), a representative component of furan-based biofuels, was selected to systematically investigate its reaction kinetic characteristics with those of NO 2 . Rate constants over a wide temperature range of 298–2400 K were calculated using multistructural canonical variational transition-state theory (MS-VTST) combined with a multidimensional tunneling correction method. The results show that the reaction rate exhibits a strong temperature dependence across the entire temperature range. This dependence is determined not only by the structure of fuel molecules but also by whether O-atom or N-atom attack occurs. In the low-temperature range (298–800 K), the combined effects of multistructural torsional anharmonicity, variational effects, and tunneling effects do not outweigh the influence of energy barrier height on reaction rates, causing the order of the rate constants to still follow the energy barrier height trend. In both NO 2 -addition and H-abstraction mechanisms, the reactions involving N-atom attack on 2EF are kinetically dominant. Notably, the tunneling effect plays a significant role in H-abstraction reactions in the low temperature range (T ⩽ 500K). This study identifies key kinetic factors governing the reaction of furan-based biofuels with NO 2, thereby providing crucial theoretical support for refining the interaction mechanism between oxygenated furan biofuels and NO X under EGR conditions.