Kohmuean Pakamas, Inthomya Worapoj, Wongkoblap Atichat, Tangsathitkulchai Chaiyot
School of Chemical Engineering, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand.
Molecules. 2021 Apr 21;26(9):2413. doi: 10.3390/molecules26092413.
Adsorption of carbon dioxide and methane in porous activated carbon and carbon nanotube was studied experimentally and by Grand Canonical Monte Carlo (GCMC) simulation. A gravimetric analyzer was used to obtain the experimental data, while in the simulation we used graphitic slit pores of various pore size to model activated carbon and a bundle of graphitic cylinders arranged hexagonally to model carbon nanotube. Carbon dioxide was modeled as a 3-center-Lennard-Jones (LJ) molecule with three fixed partial charges, while methane was modeled as a single LJ molecule. We have shown that the behavior of adsorption for both activated carbon and carbon nanotube is sensitive to pore width and the crossing of isotherms is observed because of the molecular packing, which favors commensurate packing for some pore sizes. Using the adsorption data of pure methane or carbon dioxide on activated carbon, we derived its pore size distribution (PSD), which was found to be in good agreement with the PSD obtained from the analysis of nitrogen adsorption data at 77 K. This derived PSD was used to describe isotherms at other temperatures as well as isotherms of mixture of carbon dioxide and methane in activated carbon and carbon nanotube at 273 and 300 K. Good agreement between the computed and experimental isotherm data was observed, thus justifying the use of a simple adsorption model.
通过实验和巨正则蒙特卡罗（GCMC）模拟研究了多孔活性炭和碳纳米管对二氧化碳和甲烷的吸附。使用重量分析仪获取实验数据，而在模拟中，我们使用各种孔径的石墨狭缝孔来模拟活性炭，并使用一束六边形排列的石墨圆柱体来模拟碳纳米管。二氧化碳被建模为具有三个固定部分电荷的三中心 Lennard-Jones（LJ）分子，而甲烷被建模为单个 LJ 分子。我们已经表明，活性炭和碳纳米管的吸附行为对孔径敏感，并且由于分子堆积，观察到等温线的交叉，这有利于某些孔径的相称堆积。利用纯甲烷或二氧化碳在活性炭上的吸附数据，我们推导出了其孔径分布（PSD），发现该孔径分布与从 77 K 下氮气吸附数据分析获得的 PSD 非常吻合。这个推导得到的 PSD 也用于描述其他温度下的等温线以及 273 和 300 K 时活性炭和碳纳米管中二氧化碳和甲烷混合物的等温线。计算得到的等温线数据与实验数据之间观察到了良好的一致性，从而证明了使用简单吸附模型的合理性。
