The gas adsorption/desorption experiments in coal are important contents in the research of coalbed methane (CBM) recovery and CO₂ sequestration. However, the curve of gas desorption often lags behind the adsorption curve, which is called desorption hysteresis. Desorption hysteresis is a common phenomenon that has a significant impact on the prediction of CBM recovery. In this paper, the characteristics of CH₄ and CO₂ desorption were examined using an experimental apparatus. The parameters of the Langmuir model were obtained from the desorption data. It can be concluded that the desorption isotherm of an initial pressure chosen according to the in situ coal seam pressure is more appropriate for the prediction of CBM recovery. The ratio of desorption hysteresis for CO₂ is weaker than that for CH₄ in different ranks coal. The desorption hysteresis is more likely to happen in low rank coal. The results of pore structure show that the average pore width of coal sample after CO₂ cyclic desorption experiments is changed. The pore deformation is not the primary factor that causes desorption hysteresis, and the solution phase of gas could be another factor. The findings of this study can help for better understanding of the process of CBM recovery, the production of CBM and the CO₂ storage in coal seams.

煤中的气体吸附/解吸实验是研究煤层气（CBM）回收和CO ₂固存的重要内容。但是，气体的解吸曲线通常滞后于吸附曲线，这称为解吸滞后。解吸滞后是一种普遍现象，对煤层气采收率的预测有重大影响。本文介绍了CH ₄和CO _2的特性使用实验装置检查解吸。Langmuir模型的参数是从解吸数据获得的。可以得出结论，根据原煤层压力选择的初始压力的解吸等温线更适合于煤层气采收率的预测。在不同等级的煤中，CO ₂的解吸滞后比要弱于CH ₄的解吸滞后。低阶煤更容易发生解吸滞后。孔隙结构的结果表明，CO ₂后煤样品的平均孔隙宽度循环解吸实验发生了变化。孔隙变形不是引起解吸滞后的主要因素，气体的固溶相可能是另一个因素。这项研究的结果有助于更好地了解煤层气的开采过程，煤层气的生产和煤层中的CO ₂储存。