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Molecular Dynamics Mechanism of CH4 Diffusion Inhibition by Low Temperature in Anthracite Microcrystallites.
ACS Omega ( IF 3.7 ) Pub Date : 2020-09-03 , DOI: 10.1021/acsomega.0c03381 Long Wang 1 , Zhaofeng Wang 1, 2 , Xiaojun Li 3 , Yanhui Yang 4
ACS Omega ( IF 3.7 ) Pub Date : 2020-09-03 , DOI: 10.1021/acsomega.0c03381 Long Wang 1 , Zhaofeng Wang 1, 2 , Xiaojun Li 3 , Yanhui Yang 4
Affiliation
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Understanding the adsorption/diffusion characteristics of CH4 at low temperatures (<273.15 K) is of great significance not only for coal bed methane estimation but also for gas disaster prevention and methane storage in deep coal beds. In this work, the adsorption configurations of anthracite macromolecules were constructed with Materials Studio, and then, the adsorption and diffusion behaviors of CH4 at 233.15–363.15 K were simulated, respectively, using grand canonical Monte Carlo (GCMC) and molecular dynamics (MD) algorithms. The results show that the absolute adsorption capacities of CH4 at low temperatures are substantially larger than those at high temperatures, and the adsorption amount further increases with the continued cooling at a given sorption pressure. The isosteric heat of CH4 adsorption ranges from 8.715 to 11.746 kJ/mol, belonging to a spontaneous physical adsorption. The self-diffusivity Ds of CH4 at low temperatures is substantially smaller than that at high temperatures and further decreases with cooling. The most probable velocity of CH4 molecules (vp) greatly decreases, and the number of gas molecules with a higher energy is significantly reduced by a low temperature, resulting in the diffusion inhibition of CH4.
中文翻译：
无烟煤微晶中低温抑制CH4扩散的分子动力学机理。
了解低温（<273.15 K）下CH 4的吸附/扩散特性不仅对估算煤层甲烷具有重要意义，而且对于防止瓦斯灾害和深层煤层甲烷的存储也具有重要意义。在这项工作中，利用Materials Studio构建了无烟煤大分子的吸附构型，然后分别使用大经典蒙特卡罗（GCMC）和分子动力学（MD）分别模拟了CH 4在233.15–363.15 K处的吸附和扩散行为。）算法。结果表明，CH 4的绝对吸附能力低温下的吸附量明显大于高温下的吸附量，并且在给定的吸附压力下继续冷却，吸附量进一步增加。CH 4吸附的等排热范围为8.715至11.746 kJ / mol，属于自发的物理吸附。CH 4在低温下的自扩散系数D s远小于高温下的自扩散系数，并且随着冷却而进一步降低。CH 4分子的最大可能速度（v p）大大降低，而能量较高的气体分子的数目因低温而显着减少，从而导致CH 4的扩散受到抑制。
更新日期：2020-09-15
中文翻译：
无烟煤微晶中低温抑制CH4扩散的分子动力学机理。
了解低温（<273.15 K）下CH 4的吸附/扩散特性不仅对估算煤层甲烷具有重要意义，而且对于防止瓦斯灾害和深层煤层甲烷的存储也具有重要意义。在这项工作中，利用Materials Studio构建了无烟煤大分子的吸附构型，然后分别使用大经典蒙特卡罗（GCMC）和分子动力学（MD）分别模拟了CH 4在233.15–363.15 K处的吸附和扩散行为。）算法。结果表明，CH 4的绝对吸附能力低温下的吸附量明显大于高温下的吸附量，并且在给定的吸附压力下继续冷却，吸附量进一步增加。CH 4吸附的等排热范围为8.715至11.746 kJ / mol，属于自发的物理吸附。CH 4在低温下的自扩散系数D s远小于高温下的自扩散系数，并且随着冷却而进一步降低。CH 4分子的最大可能速度（v p）大大降低，而能量较高的气体分子的数目因低温而显着减少，从而导致CH 4的扩散受到抑制。
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