Analysis of Adsorbate–Adsorbate and Adsorbate–Adsorbent Interactions to Decode Isosteric Heats of Gas Adsorption

Madani, S. Hadi; Sedghi, Saeid; Biggs, Mark J.; Pendleton, Phillip

doi:10.1002/cphc.201500881

Cited by 44 publications

(34 citation statements)

References 44 publications

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“…The PSD calculated from a QSDFT application confirmed this supposition, indicating a narrow, primary distribution of pores centred at 0.57 ± 0.05 nm, also consistent with previous studies based on repeated isotherm measurements [22] and on model-independent methods such as calorimetry and isosteric heat analyses [20,34,35].…”

Section: Resultssupporting

confidence: 89%

“…Weaker dispersion force interactions would occur on other locations of an adsorbent surface[43].Each of the above examples contains a large dipole moment: 1.9 D for 2M2B, 1.7 D for both iso-PrOH and MeOH, and 1.8 D for water. Adsorption of either of these molecules would be initially on the pore surface containing functional groups defined as high energy sites (HES), assuming steric effects were absent[35]. Subsequent adsorptive molecules would interact with the adsorbate via hydrogen bonding creating localised adsorbed-phase clusters.…”

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confidence: 99%

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Decoding gas-solid interaction effects on adsorption isotherm shape: II. Polar adsorptives

Madani

Biggs

Rodríguez‐Reinoso

et al. 2019

Microporous and Mesoporous Materials

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A unique set of 6 polar adsorptives of relatively large dipole moment and of increasing kinetic diameter were used to probe pore volumes available and their mechanism of adsorption on a wellcharacterized microporous carbon. Multiple adsorption isotherm measurements were made and repeatable results with relatively small standard deviations in amount adsorbed at low relative pressures were obtained. Inconsistencies were observed between calculated Gurvitsch volumes. Sources of these were analysed and identified as contributions from one or more of: (a) molecular sieve effects; (b) molecular packing effects, and; (c) 2D molecular structure formation due to hydrogen bonding. These inconsistencies were further studied by comparison with pore volumes derived via the Dubinin-Radushkevich (DR) equation. Qualitative analyses of the micropore filling processes were proposed, and substantiated by complementary DR analyses. Although most of the isotherms showed Type I character, recasting the relative pressure axis in logarithmic format highlighted clear differences as contributions from fluid-fluid and fluid-solid interactions during pore filling. Overall, the adsorptives were classified into three groups: (a) polar adsorptives with primarily specific interactions adsorbing as a condensation process over a relatively narrow relative pressure range in a medium and late pressure range (iso-PrOH, MeOH, 2-methyl, 2-butanol, H 2 O); (b) polar adsorptives with potential for non-specific interactions adsorbing as a condensation process over a relatively narrow pressure range in a medium pressure range (pyridine, iso-PrOH, 2-methyl, 2butanol); and, (c) halogenated adsorptives adsorbing with an S-shaped uptake extending over a broad relative pressure (dichloromethane).

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Section: Resultssupporting

confidence: 89%

mentioning

confidence: 99%

Decoding gas-solid interaction effects on adsorption isotherm shape: II. Polar adsorptives

Madani

Biggs

Rodríguez‐Reinoso

et al. 2019

Microporous and Mesoporous Materials

Self Cite

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“…The gas storage mechanisms are mainly dominated by the ratio of the interaction between gas molecules and nanopores wall to gas intermolecular interaction 8,39,59 . For gas storage in nanopores with walls of homogeneous chemical and physical properties, while the interaction between gas molecules and nanopores wall dominates (F S-F / F F-F Ͼ 1), gas storage amount first increases sharply with pressure in the low pressure region, then slowly in the relatively high pressure region 11,60 , and finally becomes a constant due to the storage saturation limited by the space available for the gas molecules 61 (see Fig. 1a).…”

Section: Behavior and Mechanisms Of Gas Storage In Nanoporous Materialsmentioning

confidence: 99%

Equation of state for methane in nanoporous material at supercritical temperature over a wide range of pressure

Chen

2016

SPE Europec Featured at 78th EAGE Conference and Exhibition

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The methane storage behavior in nanoporous material is significantly different from bulk phase, and has a fundamental role in methane extraction from shale and its storage for vehicular applications. Here we show that the behavior and mechanisms of the methane storage are mainly dominated by the ratio of the interaction between methane molecules and nanopores wall to the methane intermolecular interaction, and the geometric constraint. By linking the macroscopic properties of methane storage to the microscopic properties of methane molecules-nanopores wall molecules system, we develop an equation of state for methane at supercritical temperature over a wide range of pressure. Molecular dynamic simulation data demonstrate that this equation is able to relate very well the methane storage behavior with each of key physical parameters, including pore size, shape, wall chemistry and roughness. Moreover, this equation only requires one fitted parameter, and is simply and powerful in application.

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“…Li et al [8] and Zhao et al [9] studied the impact of temperature on the parameters in Langmuir equation, but they failed to obtain an improved Langmuir equation to precisely describe the effect of temperature or pressure variation on adsorption capacity. In addition, many studies have been reported to discuss the adsorption capacity and thermodynamic characteristics of coal from the view of energy, such as the surface free energy variation [10,11] and isosteric heat [12][13][14][15][16]. For example, [17,18] demonstrated the adsorption heat of coal on methane ranging 4-9 kJ/mol by molecular simulation.…”

Section: Introductionmentioning

confidence: 99%

Thermodynamic Characteristics of Methane Adsorption of Coal with Different Initial Gas Pressures at Different Temperatures

Cai

Feng

Jiang

et al. 2019

Advances in Materials Science and Engineering

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The adsorption of methane in coal depends on both pressure and temperature, and the adsorption gas content decreases as the temperature rises while increases as the pressure increases. When the gas molecule switches between the free state and adsorbed state, energy exchange is accompanied. To study the thermodynamic characteristics (adsorption heat, adsorption content, and adsorption time) of the methane adsorption of coal, the isothermal methane adsorption experiments of coal with different initial free gas pressures at different temperatures (30–90°C) were conducted. In this paper, a well-defined mathematical function of the adsorption heat was established on the basis of the actual gas state equation, Boltzmann energy distribution theory, and the two-state energy model, and the function was verified by the experimental data. The results show that the mathematical function of the adsorption heat can well describe the relationship among the adsorption heat, temperature, and initial free gas pressure in the closed adsorption system, and the adsorption heat involves the initial free gas pressure. The greater the initial free gas pressure, the less the adsorption heat is. In the adsorption process with different initial free gas pressures at different temperatures, the real-time free gas content increases with time and the adsorption system shows desorption process generally. For the adsorption process with the same initial free gas pressure, the adsorption time increases with the rising temperature. For the adsorption process with different initial free gas pressures at the same temperature, the greater the initial free gas pressure, the shorter the adsorption time it takes to reach an equilibrium state. The results help to understand the thermodynamic characteristics and the heat and mass transfer of methane in coal adsorption.

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Analysis of Adsorbate–Adsorbate and Adsorbate–Adsorbent Interactions to Decode Isosteric Heats of Gas Adsorption

Cited by 44 publications

References 44 publications

Decoding gas-solid interaction effects on adsorption isotherm shape: II. Polar adsorptives

Decoding gas-solid interaction effects on adsorption isotherm shape: II. Polar adsorptives

Equation of state for methane in nanoporous material at supercritical temperature over a wide range of pressure

Thermodynamic Characteristics of Methane Adsorption of Coal with Different Initial Gas Pressures at Different Temperatures

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