厘清煤中孔隙结构对甲烷吸附以及扩散的内在联系是定量评价甲烷解吸量和解吸速度的基础。运用低压氮气和低压二氧化碳吸附法对煤中多尺度孔隙进行了定量表征，获得吸附态和游离态甲烷的赋存场所和运移通道分别为0.38～1.5 nm的填充孔和1.5～100 nm的扩散孔，在此基础上建立了填充孔吸附态扩散和扩散孔游离态扩散的双孔串联扩散模型，并通过对甲烷解吸实验数据的拟合获得了甲烷扩散参数和孔隙结构参数。结果表明：基于多尺度孔隙甲烷吸附模型计算的甲烷极限吸附量与实测值匹配程度较好，其中90%以上的吸附态甲烷以微孔填充形式赋存于填充孔内，表明煤对甲烷的吸附能力取决于填充孔结构；解吸过程中填充孔内发生吸附态甲烷扩散，并不断流入扩散孔中以游离态扩散的形式流出，其中吸附态和游离态甲烷扩散系数分别处于10⁻¹³ m²/s和10⁻⁶ m²/s量级，而填充孔和扩散孔当量孔长分别为0.109～2.855 μm和0.525～3.106 mm，对应的当量孔数分别为每克10¹⁶～10¹⁷ 个和10¹⁰～10¹² 个；由于填充孔数量更多、孔长更短，吸附态甲烷浓度更高，煤中吸附态甲烷的质量传输速度要远大于扩散孔内的游离态甲烷，煤中甲烷的解吸主要受到扩散孔中游离态甲烷扩散过程的控制。

Clarifying the internal relationship between pore structure and methane adsorption and diffusion in coal is the basis for quantitative evaluation of methane desorption. The multi-scale pores in coal were quantitatively characterized by the low-pressure nitrogen and carbon dioxide adsorption methods, and the occurrence sites and migration channels of adsorbed and free methane were determined as filling pores with size of 0.38～1.5 nm and diffusion pores with size of 1.5～100 nm, respectively. A dual-pore series diffusion model of adsorbed methane in filling pores and free methane in diffusion pores was established. The methane diffusion coefficient and pore structure parameters were obtained by fitting the methane desorption data of coal particles. The results indicate that the calculated methane limiting adsorption based on multi-scale pore methane adsorption model matches the measured value well. More than 90% of adsorbed methane is stored in filled pores in the form of micropore filling, and the methane adsorption ability in coal depends on the filled pores. During methane desorption, the adsorbed methane first diffuses in filled pores, and then flows out of coal in free phase through the diffusion pores. The adsorbed and free methane diffusion coefficients are in the order of magnitude of 10⁻¹³ m²/s and 10⁻⁶ m²/s, the equivalent pore lengths of filling and diffusion pores are 0.109～2.855 μm and 0.525～3.106 mm, and the corresponding equivalent pore numbers per unit mass of coal are 10¹⁶～10¹⁷ g and 10¹⁰～10¹² g, respectively. Due to more filled pores with shorter pore lengths and higher adsorbed methane concentration, the mass transfer rate of adsorbed methane in coal is much faster than that of free methane in diffusion pores, and the methane desorption in coal is mainly controlled by the free methane diffusion process in diffusion pores.