Deconstruction of lignite macromolecular network via DMF-assisted deep eutectic solvents for directed pyrolysis valorization

Unlocking the cross-linked network structure of low-rank coal is pivotal for its high-value utilization, yet this process is severely constrained by mass transfer resistance. To address this challenge, a “carrier-permeation” synergistic strategy is proposed herein, which integrates high-permeability dimethylformamide (DMF) with high-activity deep eutectic solvents (DES). Molecular dynamics simulations indicate that DMF may function as a molecular carrier, promoting the deep penetration of viscous DES components into the coal matrix. Experimentally, this synergistic effect induces substantial physical restructuring: particle size is reduced by more than 82% (to 22.57 μm) and the aromatic interlayer spacing ( d 002 ) is increased to 0.355 nm via effective disruption of stacking interactions. Chemically, the system achieves an exceptional desulfurization rate of 90.81%, along with the selective cleavage of ether bridges and long aliphatic chains (CH 2 /CH 3 ratio minimized to 2.71). Consequently, pyrolysis pathways are substantially redirected by this structural remodeling, shifting product distribution from low-value alkanes to high-value olefins (50.47%) and esters (24.09%). A molecular-scale deconstruction system is elucidated, offering a novel approach for clean and value-added utilization of lignite.