Low‑quality coalbed methane cannot be effectively utilized due to its excessively low methane (CH₄) concentration, resulting in resource waste and greenhouse effect. Porous carbons are ideal adsorbents for CH₄/N₂ separation owing to their high specific surface area and excellent stability. However, achieving precise control over micropore size remains a significant challenge. Herein, we report a novel strategy for directly synthesizing granular carbon adsorbents with finely tuned pore structures, using a phenolic resin polymerized from resorcinol and biomass-derived furfural as the carbon precursor, eliminating the need for the exogenous binder and activator. By controlling the water/methanol solvent composition during polymerization, the micropore size of the resulting porous carbon could be precisely regulated, allowing for a uniform distribution between 0.76 and 0.90 nm. Water inhibits the active sites of phenolic resin via hydroxyl groups, reduces the cross-linking density and thermal stability, and thereby affects the pore size development of porous carbon. In situ analysis clarifies the pyrolysis and structural evolution of resins with different cross-linking densities, reveals the regulatory effect of carboxyl groups and phenoxy radicals on pore size, and confirms the dependence of porous carbon structure on precursor cross-linking as well as the feasibility of the water-mediated pore regulation strategy. Furthermore, the resulting granular porous carbon exhibits promising potential for CH₄/N₂ adsorption and separation, as evidenced by both CH₄/N₂ adsorption tests and pressure swing adsorption experiments.

granular porous carbon; CH4/N2 separation; resorcinol-furfural resin; pore size regulation;