Adsorption of argon on homogeneous graphitized thermal carbon black and heterogeneous carbon surface

D., D.; D., H.

doi:10.1016/j.jcis.2005.02.039

Cited by 24 publications

(23 citation statements)

References 31 publications

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“…2. For temperatures from 77 K to 130 K, the use of surface mediation was found to be necessary to correctly describe the adsorption of argon on GTCB (Do and Do 2005a). With the exception of 77 K (below the triple point of argon) the value of the damping constant required to fit the experimental data was found to be constant adding some weight the physical significance of surface mediation.…”

Section: Surface Mediationmentioning

confidence: 99%

On the physical adsorption of gases on carbon materials from molecular simulation

Birkett

2007

Adsorption

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In this paper we present a series of work covering a range of aspects relating molecular simulation to experiment. The importance of surface mediation type effects to the adsorption of simple and complex gases is demonstrated. Coupled with the adsorption of simple gases is their projection area when used for surface area determination. The pressure dependence of a projection area is demonstrated for argon at 77 and 87.3 K. A simple model is used to account for the degree of graphitisation of a surface is demonstrated and used to account for the isosteric heat behaviour of nongraphitised carbon blacks. Turning from surfaces to porous solids, an alternative treatment of experiment data (either sub or super critical) is presented that avoids the ambiguity of excess amounts adsorbed. Using this method one is able to obtain pore size distributions and amounts adsorbed without relying on such things as helium expansion volumes. Since this type of method is usually applied to composite solids we also demonstrate the correct method for calculating the heat of adsorption using independent sets of simulations. The final topic covered in this paper is an example of the information that can be gained from the heat capacity of an adsorbed phase. Abbreviations a m Molecular projection area nm 2 C V Heat capacity J/mol·K Surface mediation factorg(r) Radial distributionk B Boltzmann's constant J/K k sf Binary interaction parameter -L Length of simulation box nm m p Mass of adsorbent particles in cell kg N A Avogadro's number mol −1 N cell Total amount in adsorption cell mol P Pressure Pa q Partial charge on Coulombs site e Q Heat released J q st Isosteric heat kJ/mol r Separation of interaction sites nm S Particle surface area m 2 /kg V Volume m 3 z 0Distance from surface at zero potential nm ε LJ well depth J σ LJ collision diameter nm ε 0 Permittivity of a vacuum C 2 /J·m ρ s Surface density of carbon atoms nm −2 ρ b Bulk density kmol/m 3 ρ Average pore density kmol/m 3 Δ Carbon layer separation nm χ Surface mediation damping constant -Γ Surface adsorption μmol/m 2 α Volume of specific pore m 3 /kg ϕ Interaction energy J

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Section: Surface Mediationmentioning

confidence: 99%

On the physical adsorption of gases on carbon materials from molecular simulation

Birkett

2007

Adsorption

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“…The reason is due to the fact that Ar is often used in the investigations (Møller and Fort 1975;Gregg and Sing 1982;Banáres-Muńoz et al 1987;Ismail 1992;Miura and Yanazawa 2003;Do and Do 2005) similar to this study, which makes us compare easily the present data to those concerning artificial graphite samples.…”

Section: Adsorption-desorption Isotherms Of N 2 and Armentioning

confidence: 81%

“…The same feature is also found in the case of Ar adsorption. Figures 9 and 10 are the N 2 and Ar adsorption isotherm, respectively, with both axes drawn in logarithmic scale according to the literature (Kruk et al 1999;Gardner et al 2001;Do and Do 2005). The adsorbed amounts of both gases at X ≈ 0 have betrayed their real nature, as found in those figures: they are thus divided into different points on the abscissa.…”

Section: Adsorption-desorption Isotherms Of N 2 and Armentioning

confidence: 99%

The effect of burn-off on the adsorption of N2 and Ar on a natural graphite

Miura

Yanazawa²,

Nakai

2007

Adsorption

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Adsorption-desorption isotherms of N 2 and Ar were measured at 77 K using samples of graphite that were partially burned off at 600°C in O 2 gas saturated with water vapor at 25°C. The amounts of adsorbed N 2 and Ar dropped drastically as the degree of burn-off increased. The isotherms all showed a steep rise, or step, in the amounts of adsorbed N 2 and Ar at a relative pressure of around 0.4. Moreover, the hysteresis was much narrower after burn-off than before. These anomalies can be explained by the presence of functional groups on the graphite that produce H 2 O and CO 2 upon decomposition and in terms of pores on the surface of the graphite.

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“…Although there are a number of theories which have been proposed in the literature to derive this information [1][2][3][4][5][6][7][8][9][10][11][12][13], there is a need to develop tools based on molecular information to obtain a better insight into the pore structure. Density functional theory [7] or Monte Carlo simulation [14] also has been used to study the structure of porous materials structures [15]. The best information is to obtain the detailed structural arrangement of solid atoms, like the information obtained for zeolite structure.…”

Section: Introductionmentioning

confidence: 99%

Adsorption of argon on homogeneous graphitized thermal carbon black and heterogeneous carbon surface

Cited by 24 publications

References 31 publications

On the physical adsorption of gases on carbon materials from molecular simulation

On the physical adsorption of gases on carbon materials from molecular simulation

The effect of burn-off on the adsorption of N2 and Ar on a natural graphite

A new method to determine pore size and its volume distribution of porous solids having known atomistic configuration

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