A computer simulation and experimental study of the difference between krypton adsorption on a graphite surface and in a graphitic hexagonal pore

Wang, Yao; Razak, Musab Abdul; Do, D.D.; Horikawa, Toshihide; Morishige, Kunimitsu; Nicholson, D.

doi:10.1016/j.carbon.2012.02.060

Cited by 8 publications

(16 citation statements)

References 37 publications

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“…3b and c. At zero loading, the isosteric heat of 12 kJ/mol, is solely due to the interaction between krypton and graphite and is in good agreement with the calculated value (12.03 kJ/mol) from direct Monte Carlo integration [27]. As the loading in the sub-monolayer coverage region is increased, the isosteric heat increases and reaches a maximum of about 22 kJ/mol when particles in the first layer form an almost perfect hexagonal packing (Point C), consistent with observations from our previous studies [28,29]. The additional 10 kJ/mol comes from the six nearest-neighbour krypton-krypton interactions, which each contribute approximately 1.37 kJ/mol together with contributions from neighbours in more distant shells (Point C of Fig.…”

Section: Resultssupporting

confidence: 91%

A GCMC simulation and experimental study of krypton adsorption/desorption hysteresis on a graphite surface

Prasetyo

Horikawa

Phadungbut

et al. 2016

Journal of Colloid and Interface Science

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Adsorption isotherms and isosteric heats of krypton on a highly graphitized carbon black, Carbopack F, have been studied with a combination of Monte Carlo simulation and high-resolution experiments at 77K and 87K. Our investigation sheds light on the microscopic origin of the experimentally observed, horizontal hysteresis loop in the first layer, and the vertical hysteresis-loop in the second layer, and is found to be in agreement with our recent Monte Carlo simulation study (Diao et al., 2015). From detailed analysis of the adsorption isotherm, the latter is attributed to the compression of an imperfect solid-like state in the first layer, to form a hexagonally packed, solid-like state, immediately following the first order condensation of the second layer. To ensure that capillary condensation in the confined spaces between microcrystallites of Carbopack F does not interfere with these hysteresis loops, we carried out simulations of krypton adsorption in the confined space of a wedge-shaped pore that mimics the interstices between particles. These simulations show that, up to the third layer, any such interference is negligible.

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Section: Resultssupporting

confidence: 91%

A GCMC simulation and experimental study of krypton adsorption/desorption hysteresis on a graphite surface

Prasetyo

Horikawa

Phadungbut

et al. 2016

Journal of Colloid and Interface Science

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“…Their isosteric heats are distinctly different from those for simple and non-polar adsorptive [13,23]. An outstanding feature in the plot of isosteric heat versus loading is a sharp decrease at very low loadings [9,20]. This phenomenon was later explained by Horikawa et al [24]; the high heat at zero loading (greater than the heat of liquefaction) is a consequence of strong interaction between the adsorbates and functional groups.…”

Section: Introductionmentioning

confidence: 97%

“…Physical adsorption of polar fluids on graphitized thermal carbon black (GTCB) has been widely studied experimentally and theoretically [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] because an improved understanding of the interaction between the adsorbate and a graphitic surface is a fundamental step towards better design of adsorbers that use porous carbons [17][18][19][20].…”

Section: Introductionmentioning

confidence: 99%

Adsorption of water and methanol on highly graphitized thermal carbon black: The effects of functional group and temperature on the isosteric heat at low loadings

Klomkliang

Kaewmanee

Saimoey

et al. 2016

Carbon

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Isosteric heats of water and methanol adsorption on highly graphitized thermal carbon black have been studied using grand canonical Monte Carlo simulation to investigate the effects of the concentration of functional groups and temperature on the isosteric heats observed experimentally. The heat at zero loading is associated with the interaction between an adsorbate and the functional group. The variation in the heat with loading is due to a combination two effects: (1) Saturation of the functional groups by adsorbate molecules. (2) Adsorption at the convex boundary of the clusters, resulting in a lower number of neighbours for each new molecule adsorbed onto the clusters compared to the bulk liquid. The isosteric heat versus loading reaches a minimum and then increases again as the number of interactions with neighbouring molecules increases, and finally reaches the heat of liquefaction when the very large clusters approach liquid-like behaviour.

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“…Simulations below the triple point have provided better insight into these various 2D transitions at the molecular level [17,18,[27][28][29][30][31]. However, little attention has been paid to the origin of the experimentally observed hysteresis associated with the 2D transition [26,32,33].…”

Section: Introductionmentioning

confidence: 99%

On the 2D-transition, hysteresis and thermodynamic equilibrium of Kr adsorption on a graphite surface

Diao

Fan

et al. 2015

Journal of Colloid and Interface Science

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The adsorption and desorption of Kr on graphite at temperatures in the range 60 K to 88 K, was systematically investigated using a combination of several simulation techniques including: grand canonical Monte Carlo (GCMC), canonical kinetic-Monte Carlo (C-kMC) and the Mid-Density scheme (MDS). Particular emphasis was placed on the gas-solid, gas-liquid and liquid-solid 2D phase transitions. For temperatures below the bulk triple point, the transition from a 2D-liquid-like monolayer to a 2D-solid-like state is manifested as a sub-step in the isotherm. A further increase in the chemical potential leads to another rearrangement of the 2D-solidlike state from a disordered structure to an ordered structure that is signalled by (1) another sub-step in the monolayer region and (2) a spike in the plot of the isosteric heat versus density at loadings close to the dense monolayer coverage concentration. Whenever a 2D transition occurs in a grand canonical isotherm it is always associated with a hysteresis, a feature that is not widely recognized in the literature. We studied in details this hysteresis with the analysis of the canonical isotherm, obtained with C-kMC, which exhibits a van der Waals (vdW) type loop with a vertical segment in the middle. We complemented the hysteresis loop and the vdW curve with the analysis of the equilibrium transition obtained with the MDS, and found that the equilibrium transition coincides exactly with the vertical segment of the C-kMC isotherm, indicating the coexistence of two phases at equilibrium. We also analysed adsorption at higher layers and found that the 2D-coexistence is also observed, provided that the temperature is well below the triple point. Finally the 2D-critical temperatures were obtained for the first three layers and they are in good agreement with the experimental data in the literature.

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A computer simulation and experimental study of the difference between krypton adsorption on a graphite surface and in a graphitic hexagonal pore

Cited by 8 publications

References 37 publications

A GCMC simulation and experimental study of krypton adsorption/desorption hysteresis on a graphite surface

A GCMC simulation and experimental study of krypton adsorption/desorption hysteresis on a graphite surface

Adsorption of water and methanol on highly graphitized thermal carbon black: The effects of functional group and temperature on the isosteric heat at low loadings

On the 2D-transition, hysteresis and thermodynamic equilibrium of Kr adsorption on a graphite surface

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