The impact of effective pore percentage on CH4/N2 separation in coal-based activated carbon

The efficient separation of CH4/N-2 using activated carbon depends on the strict regulation of carbon pore structure. However, the relationship between pore structure and separation performance remains inadequately explored in the literature. This study employed a sample set comprising 38 coal-based granular activated carbons with diverse pore structural parameters to investigate the impact of pore size distribution on CH4/N-2 separation using advanced statistical methods. Through Pearson's correlation analysis, this study reveals that the effective pores for CH4/N-2 separation in coal-based activated carbon are those with diameters less than 1 nm, with the optimal pore size range being 0.4-0.7 nm. A novel pore structural parameter, effective pore percentage, was proposed, which exhibits a stronger correlation to separation performance and predicts the separation performance of the activated carbon more accurately than commonly used parameters. Ridge regression analysis revealed that a high proportion of effective pores (< 1 nm) generally results in higher separation efficiency, while an excessively high proportion of larger pores (> 1 nm) can diminish the separation performance ofCH(4)/N-2. This study has important implications for investigating the separation mechanism of coal-based activated carbon for CH4/N-2 and for developing efficient coal-based activated carbon for purifying coalbed gas.