Micro‐meso pore distribution correction and adsorption capacity analysis on anthracite coals by using adsorption measurements with N ₂

Abstract

Micro‐meso pore system in coal matrix plays a significant role in both green gas storage and adsorption such as coalbed methane (CBM). This paper analyzes and corrects micro‐meso pore size distribution, classifies pore system, and discusses the adsorption capacity versus multi micro‐meso pores, by using adsorption measurements with N ₂ , CO ₂ and CH ₄ on six anthracite coal samples. Pore size distributions analyzed by adsorption measurements with N ₂ and CO ₂ are consistent in the same pore size range with a generally similar trend, which is further supported by the full‐sample quantitative evidence. Thereby, the pore size distributions are corrected and merged. Three distinct micro‐meso pore systems are revealed by using fractal theory. Pore III is mesopore and refers to those pores with pore size larger than 10 nm, while pores I and II represent micropores with an inflection point of 5 nm. Pore II possesses the most complex pore structure among the three pore types, and pore I has the simplest pore structure. Langmuir pressure and Langmuir volume are both related to the whole micro‐meso pore system and are not controlled by any single pore type. The micro‐meso pore structure exerts a strong influence on Langmuir pressure, with micropores playing a more dominant role than mesopores, particularly for pore II. The surface area ratio ( S _r ) is proposed in this study, and exhibits a positive linear correlation with Langmuir volume.