On the adsorbate restructuring induced hysteresis of simple gas adsorption in slit micropores

Diao, Rui; Fan, Chunyan; Do, D.D.; Nicholson, D.

doi:10.1016/j.cej.2016.01.072

Cited by 5 publications

(4 citation statements)

References 44 publications

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“…Low-permeability heterogeneous reservoirs are mostly developed with micro-nano-scale pore throats, which generate high capillary pressure and lead to adsorption hysteresis effect. This adsorption hysteresis effect obviously affects the critical properties and phase behavior of fluids [14][15][16]. The critical shift parameter is measured using the corresponding correlation proposed by Zarragoicoechea et al [17]:…”

Section: Modified Equation Of Statementioning

confidence: 99%

A Determination Method of CO2-Oil Miscible State in the Heterogeneous Low-Permeability Reservoir

Lili¹,

Jiang²,

Tian³

et al. 2022

Preprint

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CO 2 flooding can effectively enhance the recovery of low-permeability reservoirs and realize CO 2 storage. However, the strong heterogeneity of low permeability reservoirs makes it difficult to accurately determine the miscible state of CO2 and oil. In this study, first, a PR-EOS is modified by considering the shifts of critical properties. Second, the parachor model is coupled with the modified PR-EOS to predict the minimum miscible pressure (MMP). Third, considering the multiple contact process between CO 2 and oil, a MMP prediction model based on the microscopic heterogeneity is established. Afterwards, the model calculation results are compared with the prior experimental results of CO 2 flooding to verify its applicability and superiority. Finally, the model is applied to the actual low-permeability reservoir to determine the miscible state of CO 2 and oil.

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Section: Modified Equation Of Statementioning

confidence: 99%

A Determination Method of CO2-Oil Miscible State in the Heterogeneous Low-Permeability Reservoir

Lili¹,

Jiang²,

Tian³

et al. 2022

Preprint

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“…The numerous slit-type and round-type pore structures below 10 nm diameter were found on the surface of coal (lignite from the Xilinhot region of Inner Mongolia, China) by scanning electron microscopy (SEM) techniques, as shown in Figure 1 a-c. When studying the coal pore structure on gas adsorption characteristics, the graphite slit model was often used [13,31,35,37,51], as shown in Figure 1 d. As in Figure 1(c), the default distance between graphite slit models in the molecular simulation software was H, but the distance between the pore walls of coal in the actual case was H`, the conversion equation between H and H` was as follows.…”

Section: Modelsmentioning

confidence: 99%

“…At the same time, coal is a cross-linked molecule with high molecular weight [7]. In order to simplify the molecular structure of coal, scholars mostly adopted the graphite slit model with regular arrangement of carbon atoms to study the effect of coal pore structure on gas adsorption, and the results obtained by molecular simulation showed good similarity with the experimental results [35][36][37].…”

mentioning

confidence: 93%

O2 Physisorption in Coal Pore: Effects of Pore Size, Pressure, Temperature and Function Group

Cheng

Tan

et al. 2022

Preprint

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In this paper, the physical adsorption characteristics of oxygen in coal pores were systematically investigated by the Grand Canonical Monte Carlo and the COMPASS force field. Firstly, coal pore structures of different sizes were constructed by graphite slit models and different groups. Secondly, the physisorption behavior of oxygen in graphite slit models of different sizes was simulated. Finally, the physisorption behavior of oxygen in graphite slit models at different pressures and temperatures was analyzed. The results showed that the physisorption density and excess physical adsorption of oxygen were divided into the rapidly decreasing stage (0.4-0.7 nm), the slowly decreasing stage (0.7-1.4 nm), and the stable stage (1.4 nm-5 nm) with the increase of coal pores, and the excess oxygen physisorption amount was more sensitive to the change of pressure. The O2 isosteric heat of physisorption decreased with increasing pore size of coal. Oxygen is more strongly adsorbed by hydroxyl and ether bonds than by methyl, carboxyl and carbonyl groups. Through this study, the mechanism of oxygen physical adsorption in coal pores and the characteristics influenced by temperature and pressure can be better understood.

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“…In a closed-end pore, the isotherms were found to be reversible for all pore sizes studied, because the closed end acts as a nucleation site for the liquid condensate to form. There is a hysteresis loop associated with restructuring of the condensate in both the open and closed end pores of 1.5nm width over a pressure range above the condensation pressure 149 . To elucidate the mechanism of the restructuring we present, in Figure 6.7, the local density distributions and snapshots just before and just after Points A and B in Figure 6 5.30kJ/mol, respectively.…”

Section: Effects Of Pore Sizementioning

confidence: 99%

Fundamental study of adsorption and desorption process in porous materials with functional groups

Zeng¹

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Adsorption is used in industries for gas separation and purification because of its less energy intensive than other traditional separation processes, such as distillation and gas absorption.However, its effective application depends on the theoretical understanding of the underlying phenomena of adsorption of molecules in porous solid adsorbents. With the advances in molecular simulation techniques, investigation into the microscopic mechanisms of adsorption phenomena can be realized and this will lead to a development of an unambiguo us approach for the characterization of porous solids. This is the aim of this project to understand adsorption and desorption mechanisms in porous materials, especially porous carbons with functional groups because they are not fully studied in the literature.One of the significant points of this thesis is the development of a novel molecular model for porous carbon. Graphitized thermal carbon black (GTCB) was used as model adsorbent modelled as a composite of basal plane of graphene layers with crevices (ultrafine micropores) and oxygen functional groups attached at the edges of the graphene layers. This model was used in adsorption of various gases, and was validated with high resolution experimental data and theoretically analysed with simulation results obtained with a grand canonical Monte Carlo simulation.Excellent agreement between the experimental data and the simulation results has led us to derive the structural properties of GTCB and the nature of the functional group. Furthermore, the experimental Henry constant and the isosteric heat at zero loading (in the region of very low loadings) are described correctly with the Monte Carlo integration of the Boltzmann factor of the pairwise interaction between an adsorbate molecule and the porous carbon. It was found that adsorbate dominantly adsorbs in the fine crevices at very low loadings because of the enhancement of the solid-fluid potential energy, followed by adsorption on the basal plane of graphene layers. This is the case for non-polar fluids, such as argon and nitrogen. On the other hand, polar fluids, such as ammonia and water, the dominance of the functional group in adsorption is manifested, especially water.This novel model for carbon can be extended to describe practical porous carbons containing both micropores (for adsorptive capacity) and mesopores (for transport). Adsorption in mesopores is associated with capillary condensation and evaporation, and the se are commonly used in the literature to derive the mesopore size distribution. For this determination to be realized, the fundamental understanding of condensation and evaporation must be understood, and this is the second objective of this thesis. We chose graphitic slit pores to model the mesopore, and investigated the effects of various parameters on the capillary condensation and evaporation. Grand ii canonical Monte Carlo technique is used to obtain the isotherm and the isosteric heat, and we particularly investigate the mechanisms of adsorpti...

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On the adsorbate restructuring induced hysteresis of simple gas adsorption in slit micropores

Cited by 5 publications

References 44 publications

A Determination Method of CO2-Oil Miscible State in the Heterogeneous Low-Permeability Reservoir

A Determination Method of CO2-Oil Miscible State in the Heterogeneous Low-Permeability Reservoir

O2 Physisorption in Coal Pore: Effects of Pore Size, Pressure, Temperature and Function Group

Fundamental study of adsorption and desorption process in porous materials with functional groups

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