Geoenvironmental Research Centre (GRC), School of Engineering, Cardiff University, The Queen's Buildings, The Parade, Cardiff CF24 3AA, U.K.
Langmuir. 2023 Jan 31;39(4):1548-1561. doi: 10.1021/acs.langmuir.2c02971. Epub 2023 Jan 20.
This study focuses on improving fundamental understanding of low, subcritical CO adsorption-desorption behavior of bituminous coals with the aim to evaluate the utility of shallow-depth coal seams for safe and effective CO storage. Comprehensive data and a detailed description of coal-CO interactions, e.g., adsorption, desorption, and hysteresis behavior of intact bituminous coals at CO pressures <0.5 MPa, are limited. Manometric sorption experiments were performed on coal cores (50 mm dia. and 30- or 60-mm length) obtained from a 30 m deep coal seam located at the Upper Silesian Basin in Poland. Experimental results revealed that the adsorption capacities were correlated to void volume and equilibrium time under low-pressure injection (0.5 MPa). The positive deviation, observed in the hysteresis of adsorption-desorption isotherm patterns, and the increased sample mass at the end of the tests suggested CO pore diffusion and condensation. This behavior is vital for assessing low-pressure CO injection and storage capabilities of shallow coal seams where confining pressure is much lower than that of the deeper seams. Overall, CO adsorption depicts a type II adsorption isotherm and a type H3 hysteresis pattern of the IUPAC classification. Experimental results fitted better to the Brunauer-Emmett-Teller model than the Langmuir isotherm model. CO adsorption behavior of intact cores was also evaluated by characteristic curves. It was found that Curve I favored physical forces, i.e., the presence of van der Waals/London dispersion forces to describe the coal-CO interactions. However, analysis of Curve II indicated that the changing pressure-volume behavior of CO in the adsorbed phase, under low equilibrium pressures, cannot be ignored.
本研究旨在深入了解烟煤在低、亚临界条件下 CO 吸附-解吸的基本行为，以评估浅层煤层安全有效储存 CO 的潜力。目前对于烟煤在 CO 压力<0.5 MPa 条件下的 CO-煤相互作用，如吸附、解吸和滞后行为，缺乏全面的数据和详细描述。通过对取自波兰上西里西亚盆地 30m 深煤层的煤芯（直径 50mm，长度 30 或 60mm）进行压力容量法吸附实验，获得了相关数据。实验结果表明，在低压注入（0.5 MPa）条件下，吸附容量与空隙体积和平衡时间相关。在吸附-解吸等温线滞后模式中观察到的正偏差，以及测试结束时样品质量的增加，表明 CO 发生了孔隙扩散和凝聚。这种行为对于评估浅层煤层的低压 CO 注入和储存能力非常重要，因为浅层煤层的围压远低于深层煤层。总体而言，CO 吸附表现出 II 型吸附等温线和 IUPAC 分类中的 H3 滞后模式。实验结果更符合 Brunauer-Emmett-Teller 模型，而非 Langmuir 等温线模型。通过特征曲线还评估了完整煤芯的 CO 吸附行为。结果表明，曲线 I 有利于物理力，即存在范德华/伦敦色散力来描述 CO-煤相互作用。然而，对曲线 II 的分析表明，在低平衡压力下，吸附相中 CO 的压力-体积变化行为不容忽视。
