(Theme session) Recent Trends in the Development and Utilization of Coal and Other Energy Sources

10:35 AM - 10:55 AM JST(1:35 AM - 1:55 AM UTC)

[3101-07-04] Molecular Simulation of Coal Pyrolysis for Hydrogen Production: A ReaxFF MD Study

○Shi Ying^{3,2[Student presentation: Doctoral course]}, Yuichi Sugai¹, Zhu Yanming² (1. Faculty of Engineering, Kyushu University, 2. School of Resources and Geosciences, China University of Mining and Technology, 3. Graduate School of Engineering, Kyushu University)

司会：菅井裕一（九州大学）

Keywords:

Coal pyrolysis,Hydrogen production,Molecular structure,ReaxFF MD simulation,Radical mechanism

Hydrogen is a promising clean energy carrier with significant potential in transportation, power generation, and the chemical industry. In China, coal remains the primary source of hydrogen, making coal-to-hydrogen technologies essential for the country’s energy transition. This study investigates the pyrolysis mechanisms of Dananhu (DNH) coal from China for hydrogen production using a reactive force field molecular dynamics (ReaxFF MD) approach. The DNH sample, a Jurassic long-flame coal from the Tuha Basin, features high volatile content and hydrogen-rich aliphatic structures. Elemental analysis, ¹³C nuclear magnetic resonance (NMR), and X-ray photoelectron spectroscopy (XPS) were employed to analyze the sample’s chemical composition and functional groups. Based on the structural parameters derived from these methods, a macromolecular model of the coal (C₁₄₂H₁₈₁O₁₇N) was constructed and validated through comparison with the experimental ¹³C NMR spectrum. The three-dimensional molecular structure was then optimized and applied in ReaxFF MD simulations using LAMMPS software. Simulation results revealed a multi-stage hydrogen evolution mechanism. At temperatures below 1600 K, physically adsorbed gases such as H₂O and CO₂ were primarily released. Between 1600 and 2800 K, H₂O, CO₂, CH₄, and H₂ were generated, with hydrogen evolution driven mainly by the cleavage of aliphatic C–H and hydroxyl O–H bonds. At higher temperatures (2800–4000 K), intensified polycondensation and aromatic radical formation led to significant H₂ production. Bond cleavage analysis showed that over 50% of hydrogen originated from the detachment of hydrogen atoms from functional groups, followed by radical recombination. This study offers molecular-level insight into temperature-dependent hydrogen generation during coal pyrolysis, supporting cleaner and more efficient hydrogen production from coal.