Jia Jinzhang, Song Hailong, Jia Peng
College of Safety Science and Engineering, Liaoning Technical University, Fuxin123000, Liaoning, China.
Key Laboratory of Mine Thermal Power Disaster and Prevention, Ministry of Education, Fuxin123000, Liaoning, China.
ACS Omega. 2023 Jan 10;8(3):3461-3469. doi: 10.1021/acsomega.2c07471. eCollection 2023 Jan 24.
Obvious differences exist in the structures of different coal rank coals, resulting in many differences and similarities in the amount of methane (CH) gas adsorbed by coal and the control mechanism. In this study, we conducted adsorption simulations of three different coal rank coals in the superposition state using the Materials Studio software with simulated temperatures of 293.15, 313.15, and 333.15 K and adsorption pressures ranging from 0 to 10 MPa. We used the grand canonical ensemble Monte Carlo calculation method to calculate and study the adsorption amount, adsorption process, isosteric heat, and diffusion coefficient of CH in detail. We found that the adsorption of CH by coal samples of three coal rank coals (i.e., anthracite, bituminous coal, and lignite), which were mixed and stacked separately, was concentrated in the effective pores of coal molecules. Their effect on the amount of CH adsorption was dominated by the coal samples with more effective pores in the coal molecules. The isosteric heat of the coal samples showed an obvious exponential relationship with the adsorption pressure, and the isosteric heat of coal samples as a nonhomogeneous adsorbent gradually decreased with an increase in adsorption pressure. During the transformation of free-state CH into an adsorbed state, we obtained the best adsorption effect for bituminous-lignite superposition-state coal samples, and the diffusion coefficient of CH was the lowest.
不同煤阶煤的结构存在明显差异，导致煤吸附甲烷（CH）气体的量及控制机制存在诸多异同。本研究利用Materials Studio软件，在模拟温度为293.15、313.15和333.15 K且吸附压力为0至10 MPa的条件下，对三种不同煤阶煤在叠加状态下进行了吸附模拟。采用巨正则系综蒙特卡罗计算方法，详细计算并研究了CH的吸附量、吸附过程、等量吸附热和扩散系数。我们发现，三种煤阶煤（即无烟煤、烟煤和褐煤）单独混合堆积的煤样对CH的吸附集中在煤分子的有效孔隙中。它们对CH吸附量的影响主要由煤分子中有效孔隙较多的煤样主导。煤样的等量吸附热与吸附压力呈明显的指数关系，且作为非均相吸附剂的煤样等量吸附热随吸附压力的增加而逐渐降低。在游离态CH转化为吸附态的过程中，烟煤 - 褐煤叠加态煤样的吸附效果最佳，且CH的扩散系数最低。
