Ca-catalysis mechanisms from coal pyrolysis to high energy density fuel precursors: Multiscale insights via ReaxFF MD and experiment

The development of coal-based high-energy-density (HED) aviation fuels is critical for advancing diversified energy strategies in the aviation industry. A core scientific challenge lies in the directional regulation of naphthalene (a key HED precursor) generation during coal pyrolysis. This study integrates experimental methods with Reactive Force Field molecular dynamics (ReaxFF MD) simulations, revealing for the first time the detailed reaction pathway of naphthalene formation and the calcium catalytic enhancement mechanism. By tracking carbon skeleton evolution, we construct a quantitative reaction network for naphthalene generation and identified eight distinct pathways, including a previously unreported route involving the cleavage–recombination of monocyclic aromatic C₁₃H₁₈. Experimental results demonstrate that the introduction of calcium significantly accelerates the macromolecular cracking rate, with an increase of up to 75 %; by catalyzing new pathways and promoting naphthol dehydroxylation, the yield of naphthalene derivatives is effectively increased by 56 % under experimental conditions. This study offers critical theoretical guidance and technical support for optimizing coal-based HED fuel precursor production and designing efficient calcium-based catalysts.