Molecular Mechanisms of the Effect of Water on CO2/CH4 Mixture Adsorption in Slitlike Carbon Pores

Sizova, Anastasia A.; Sizov, V. V.; Brodskaya, E. N.

doi:10.1134/s1061933x18040117

Cited by 6 publications

(8 citation statements)

References 24 publications

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“…Pore size is another parameter affecting the adsorption amount. In micropores, the excess adsorption amount grows with the pore size, while the mesopore exhibits opposite effect, ,,,,,,,,, as shown in Figure . These trends are attributed to the superimposed effect of the pore wall, which decreases with increase of the mesopore size, thereby reducing the adsorption amount. ,,, Additionally, the enlarged pore volume provides more space for the adsorbate to travel in and thus a reduced force between the adsorbate and adsorbent; consequently, a reduction in the adsorption amount is observed. , At a given instant, a micropore has more surface area than a mesopore for an equivalent pore volume .…”

Section: Simulation Resultsmentioning

confidence: 96%

“…Moisture has a comprehensive negative effect on adsorption. ,,,, The absolute and excess adsorption amounts of CH 4 and CO 2 become reduced as H 2 O molecules occupy both adsorption sites and the effective adsorption space in the pore volume . This effect is attributed to the strong electric dipole and polar nature of H 2 O, which leads to stronger interactions with coal models. ,,, As shown in Figure , increasing the moisture content is not conducive to CH 4 adsorption for different carbon content models . According to the energy analysis in Figure , the potential energy changes little with the increase in moisture content (from 0 to 8%), which implies that the change in the interaction between H 2 O and the adsorbent is not noticeable, whereas the CH 4 adsorption amount drops by 1.5 times, indicating that H 2 O molecules hinder the CH 4 adsorption process by occupying the adsorption space rather than adsorption sites .…”

Section: Simulation Resultsmentioning

confidence: 98%

“…The μVT ensemble has been carried out to derive the isothermal adsorption for micropores at a constant chemical potential. ,,,,, It is also used to simulate the adsorption behavior for porous coal models with functional groups . Liu et al undertook the μVT ensemble to investigate the adsorption isotherms on a perfect graphene surface, which matched the type I Langmuir model well and was also in line with the experimental results …”

Section: Simulation Methodsmentioning

confidence: 88%

“…Adsorption selectivity is a criterion to evaluate the preferential adsorbing performance of a binary mixture. ,,,,, It is usually employed to define the competitive adsorption behaviors and is expressed as follows: where S stands for the adsorption selectivity, x is the adsorbate mole fraction in the adsorbed phase, and y is the adsorbate mole fraction in the bulk phase; each value is a dimensionless number. ,,,,, …”

Section: Simulation Resultsmentioning

confidence: 99%

“…Because of the presence of these functional groups, the partial charges should be considered. The OPLS force field was used to define the partial charges . Additionally, the Amber force field was adopted to determine the bond parameters and to verify that each C atom was attached to no more than two functional groups .…”

Section: Simulation Methodsmentioning

confidence: 99%

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Simulation of Adsorption–Desorption Behavior in Coal Seam Gas Reservoirs at the Molecular Level: A Comprehensive Review

Wang

Chen

et al. 2020

Energy Fuels

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This work reviews the processes of methane (CH4) and carbon dioxide (CO2) adsorption and desorption, as well as the displacement of CH4 by CO2, at the molecular level. For the adsorbate, laboratory experiments and numerical simulations have been carried out to examine the adsorption and desorption behavior of CH4 and CO2. For the adsorbent, graphite, graphene, carbon nanotube, and heteroatom-containing carbon-based models have been developed for adsorption and desorption processes. In recent decades, simulations of carbon dioxide enhanced coalbed methane (CO2-ECBM) have achieved significant progress. This success has generated significant interest among the scientific communities, as coalbed methane is one of the cleanest forms of energy. Furthermore, an improved understanding of this process can help to sequester CO2 in deep unminable coal seam gas reservoirs to mitigate CO2 emission. This work reviews the advantages and weaknesses of three simulation methods, namely, molecular dynamics (MD), Monte Carlo (MC), and the density functional theory (DFT), with respect to their applications in CO2-ECBM and CO2 sequestration in CBM. Based on such simulations, dynamic and thermodynamic properties have been analyzed to evaluate the effectiveness of CO2-ECBM and CO2 sequestration. In recent studies, MD simulation has been commonly used to optimize the configuration of the adsorbate and adsorbent, as well as to define the self-diffusion coefficient and mean squared distance. However, this approach only works for a small atomic system or a short time simulation process. MC, on the other hand, is used to predict the adsorption behavior of pure component and binary and ternary mixtures of adsorbates. Nevertheless, the simulation cannot obtain information on the dynamic processes. Meanwhile, DFT is commonly used to predict the adsorption site, orientation, and adsorption energy. Dynamic and thermodynamic properties are discussed based on the three simulation methods. Certain aspects facing the future are also addressed.

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