Swelling Pretreatment Enhances Anthracite Gasification in Supercritical Water via Pore-Catalyst-Radical Synergy

Supercritical water gasification (SCWG) of anthracite is hindered by its dense structure and low reactivity. This study demonstrates that solvent swelling pretreatment dramatically enhances anthracite gasification via pore-catalyst-radical ternary coupling mechanism. The SCWG of benzene-swollen anthracite was systematically investigated through a suite of integrated experiments. The pretreatment induces significant pore reconstruction, creating a hierarchical network that improves mass transfer and facilitated the diffusion of hydroxyl radicals (·OH). This pore expansion synergized with inherent alkali catalysts, steering mineral transformation towards kalsilite and enhancing catalytic activity. Consequently, the formation of refractory polycyclic aromatic hydrocarbons in the liquid phase was suppressed, while the yield of readily gasifiable oxygenates increased. A novel three-phase kinetic model was developed, quantitatively describing dynamic carbon migration and validating the ternary coupling mechanism. Remarkably, the swollen anthracite achieved a carbon gasification efficiency of 96.03% and a high H₂ yield of 62.05 mol/kg at 750 °C in batch reactor. This work provides fundamental insights and a kinetic framework for the efficient utilization of high-rank coals via SCWG.