Microstructural modulation via solvent swelling synergistically enhances anthracite gasification in supercritical water

The dense nature of anthracite significantly limits its conversion efficiency in supercritical water gasification (SCWG). This study addresses this fundamental challenge by proposing a facile solvent swelling pretreatment to reconstruct the coal's microstructure. A screening study of nine solvents revealed a distinct structure–activity relationship. Benzene, as a non-polar solvent, was the most effective, causing a remarkable 303 % volumetric expansion and markedly enhancing the pore structure by increasing the mesopore ratio from 28 % to 52 %. Concurrently, the pretreatment enriched surface carboxyl groups (increased by 60.4 % to 0.85 μmol/g), facilitating catalytic decarboxylation. These synergistic microstructural modifications drastically enhanced the SCWG performance at 750 ℃ and 25 MPa, boosting the carbon gasification efficiency from 83.5 % to 96.0 % and the H₂ yield by 14.2 %. Critically, this work overcomes the long-standing challenge of applying solvent swelling to anthracite, a material traditionally considered recalcitrant to such pretreatment. This study thereby demonstrates a highly effective pretreatment strategy, with the significant microstructural modulation and performance enhancement offering a promising and scalable pathway towards improving the economic viability and carbon conversion efficiency of industrial-scale SCWG processes.