Co-combustion characteristics of ammonia and ethanol: A combined ReaxFF- MD and DFT study

MH Xu and JF Li and M Ma and XH Zhang and LY Chen and H Wang and R Chen, JOURNAL OF THE ENERGY INSTITUTE, 123, 102258 (2025).

DOI: 10.1016/j.joei.2025.102258

Ammonia (NH3), as a "carbon-free" hydrogen energy carrier, is an excellent alternative to traditional fuels. It can improve combustion efficiency when co-burning with ethanol (C2H5OH). However, the research on the co-combustion characteristics of these two substances at the microscopic level is still incomplete. Therefore, the methods of ReaxFF molecular dynamics simulation and density functional theory are adopted to explore the combustion mechanisms of NH3 and C2H5OH. The calculation results show that C2H5OH first pyrolyzes thermally to generate free radicals such as OH and H, which promotes the oxidation of NH3 through a series of hydrogen abstraction reactions. Among them, the OH free radical obtains a kinetic advantage with its lowest energy barrier, thus playing a major role in promoting the oxidation of NH3. During the oxidation process, the amino group generates a variety of different intermediate products with the transfer of nitrogen elements, such as HNO, NH, and N2H4. The alkyl radicals CH3 and C2H5 mainly participate in the subsequent cyanidation reaction with NH2 and finally generate HCN. These findings provide mechanistic insights that support kinetic model development and nitrogen-species control strategies.

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