Almolliyeh Maram, Tripathy Snehasis, Sadasivam Sivachidambaram, Masum Shakil, Thomas Hywel Rhys
Geoenvironmental Research Centre (GRC), School of Engineering, Cardiff University, The Queen's Buildings, The Parade, Cardiff, CF24 3AA, United Kingdom.
ACS Omega. 2023 Feb 10;8(7):7070-7084. doi: 10.1021/acsomega.2c07940. eCollection 2023 Feb 21.
This study examines the influence of subcritical pressure and the physical nature (intact and powder) of coal samples on CO adsorption capacity and kinetics in the context of CO sequestration in shallow level coal seams. Manometric adsorption experiments were carried out on two anthracite and one bituminous coal samples. Isothermal adsorption experiments were carried out at 298.15 K in two pressure ranges: less than 6.1 MPa and up to 6.4 MPa relevant to gas/liquid adsorption. The adsorption isotherms of intact anthracite and bituminous samples were compared to that of the powdered samples. The powdered samples of the anthracitic samples had a higher adsorption than that of intact samples due to the exposed adsorption sites. The intact and powdered samples of bituminous coal, on the other hand, exhibited comparable adsorption capacities. The comparable adsorption capacity is attributed to the intact samples' channel-like pores and microfractures, where high density CO adsorption occurs. The adsorption-desorption hysteresis patterns and the residual amount of CO trapped in the pores reinforce the influence of the physical nature of the sample and pressure range on the CO adsorption-desorption behavior. The intact 18 ft AB samples showed significantly different adsorption isotherm pattern to that of powdered samples for experiments conducted up to 6.4 MPa equilibrium pressure due to the high-density CO adsorbed phase in the intact samples. The adsorption experimental data fit into the theoretical models showed that the BET model fit better than the Langmuir model. The experimental data fit into the pseudo first order, second order, and Bangham pore diffusion kinetic models showed that the rate-determining steps are bulk pore diffusion and surface interaction. Generally, the results obtained from the study demonstrated the significance of conducting experiments with large, intact core samples pertinent to CO sequestration in shallow coal seams.
本研究在浅层煤层CO封存背景下，考察亚临界压力和煤样物理性质（完整和粉末状）对CO吸附容量及动力学的影响。对两个无烟煤和一个烟煤样品进行了压力吸附实验。在298.15 K下，于两个压力范围进行等温吸附实验：低于6.1 MPa以及高达与气/液吸附相关的6.4 MPa。将完整无烟煤和烟煤样品的吸附等温线与粉末状样品的吸附等温线进行了比较。由于吸附位点暴露，无烟煤粉末状样品的吸附量高于完整样品。另一方面，烟煤完整和粉末状样品表现出相当的吸附容量。这种相当的吸附容量归因于完整样品中类似通道的孔隙和微裂缝，在那里会发生高密度CO吸附。吸附 - 解吸滞后模式以及孔隙中截留的CO残留量强化了样品物理性质和压力范围对CO吸附 - 解吸行为的影响。对于在高达6.4 MPa平衡压力下进行的实验，完整的18英尺AB样品与粉末状样品相比，吸附等温线模式显著不同，这是由于完整样品中存在高密度CO吸附相。吸附实验数据与理论模型拟合表明，BET模型比Langmuir模型拟合得更好。实验数据与伪一级、二级和Bangham孔扩散动力学模型拟合表明，速率决定步骤是大孔扩散和表面相互作用。总体而言，该研究所得结果表明，对与浅层煤层CO封存相关的大型完整岩心样品进行实验具有重要意义。
