ReaxFF Molecular Dynamics Study on Nitrogen-Transfer Mechanism in the Hydropyrolysis Process of Lignite

•Nitrogen-transfer mechanism of lignite hydropyrolysis is investigated by ReaxFF MD.•Products distribution and reaction pathways agreed well with reported experimental data.•Hydrogen accelerated transfer of nitrogen atoms from solid to liquid and gas phases.•Hydrogen hindered the cross-linking of CC and CN bonds.•HCN and NH3 are produced with nitrile and CH2NH as their precursors.