Water‐Mediated Tailoring of Pore Structure in Phenolic Resin‐Based Porous Carbons for Enhancing CH ₄ /N ₂ Adsorption Separation

ABSTRACT Porous carbons are ideal adsorbents for gas separation owing to their 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 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 exhibited promising potential for CH 4 /N 2 adsorption and separation, as evidenced by both CH 4 /N 2 adsorption tests and pressure swing adsorption experiments.