A new determination method of absolute adsorption isotherm of supercritical gases under high pressure with a special relevance to density-functional theory study

Murata, Katsuyuki; El-Merraoui, M.; Kaneko, Katsumi

doi:10.1063/1.1344926

Cited by 131 publications

(98 citation statements)

References 53 publications

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“…Unfortunately, it cannot be obtained experimentally, because the location of the Gibbs' interface, as well as the volume and the density of the adsorbed phase (α phase density) cannot be measured [11,12]. This disadvantage from a practical point of view, for example for gas storage application, can be well solved by using the total storage capacity concept, which is the most reliable value that can be obtained.…”

Section: Introductionmentioning

confidence: 99%

“…are interesting candidates for gas storage application [8][9][10]. In the case of supercritical gases, the adsorbed phase cannot condensate, presenting a density gradient inside the Gibbs' interface [11][12][13]. This is particularly important for supercritical gases with low molecular weight and relatively weak gassolid interactions such as hydrogen [14].…”

Section: Introductionmentioning

confidence: 99%

“…The schematic diagram in Figure 1 plots the adsorbate density over the distance from the adsorbent, showing the different phases. The α phase corresponds to the density of the adsorbed surface excess, while the β and γ phases correspond to the density of the gas which is stored due to compression inside the adsorbent's void space, i.e., inside its pores and the inter-particle space, respectively [11]. Initially, the densities of all of the phases increase with increasing pressures.…”

Section: Introductionmentioning

confidence: 99%

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Adsorbent density impact on gas storage capacities

Kunowsky¹,

Suárez-Garcı́a²,

Linares‐Solano³

2013

Microporous and Mesoporous Materials

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In the literature, different approaches, terminologies, concepts and equations are used for calculating gas storage capacities. Very often, these approaches are not well defined, used and/or determined, giving rise to significant misconceptions. Even more, some of these approaches, very much associated with the type of adsorbent material used (e.g., porous carbons or new materials such as COFs and MOFs), impede a suitable comparison of their performances for gas storage applications. We review and present the set of equations used to assess the total storage capacity for which, contrarily to the absolute adsorption assessment, all its experimental variables can be determined experimentally without assumptions, ensuring the comparison of different porous storage materials for practical application. These materialbased total storage capacities are calculated by taking into account the excess adsorption, the bulk density (ρ bulk ) and the true density (ρ true ) of the adsorbent. The impact of the material densities on the results are investigated for an exemplary hydrogen isotherm obtained at room temperature and up * Tel.: +34 965 90 93 50; Fax: +34 965 90 34 54.Email address: kunowsky@ua.es (Mirko Kunowsky) February 5, 2013 to 20 MPa. It turns out that the total storage capacity on a volumetric basis, which increases with both, ρ bulk and ρ true , is the most appropriate tool for comparing the performance of storage materials. However, the use of the total storage capacities on a gravimetric basis cannot be recommended, because low material bulk densities could lead to unrealistically high gravimetric values. Preprint submitted to Microporous and Mesoporous Materials

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Adsorbent density impact on gas storage capacities

Kunowsky¹,

Suárez-Garcı́a²,

Linares‐Solano³

2013

Microporous and Mesoporous Materials

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“…This results in the phenomenon that the adsorptive capacity measured experimentally represents the maximum value and then declines, i.e., there is a large difference between the measured apparent adsorption capacity and the absolute adsorptive capacity. To help solve this problem, some correction models for calculating the adsorptive capacity are introduced (Haydel and Kobayashi 1967;Murata et al 2001), and a relatively common method is as follows:…”

Section: Theory Of Adsorption Of Gas In Coal Seams and The Experimentmentioning

confidence: 99%

Contribution of moderate overall coal-bearing basin uplift to tight sand gas accumulation: case study of the Xujiahe Formation in the Sichuan Basin and the Upper Paleozoic in the Ordos Basin, China

et al. 2015

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Tight sand gas is an important unconventional gas resource occurring widely in different petroleum basins. In coal-bearing formations of the Upper Triassic in the Sichuan Basin and the Carboniferous and Permian in the Ordos Basin, coal measure strata and tight sandstone constitute widely distributed source-reservoir assemblages and form the basic conditions for the formation of large tight sand gas fields. Similar to most tight gas basins in North America, the Sichuan, and Ordos Basins, all experienced overall moderate uplift and denudation in MesoCenozoic after earlier deep burial. Coal seam adsorption principles and actual coal sample simulation experiment results show that in the course of strata uplift, pressure drops and desorption occurs in coal measure strata, resulting in the discharge of substantial free gas. This accounts for 28 %-42 % of total gas expulsion from source rocks. At the same time, the free gases formerly stored in the pores of coal measure source rocks were also discharged at a large scale due to volumetric expansion resulting from strata uplift and pressure drop. Based on experimental data, the gas totally discharged in the uplift period of Upper Paleozoic in the Ordos Basin, and Upper Triassic Xujiahe Formation in the Sichuan Basin is calculated as (3-6) 9 10 8 m 3 /km 2 . Geological evidence for gas accumulation in the uplift period is found in the gas reservoir analysis of the above two basins. Firstly, natural gas discharged in the uplift period has a lighter carbon isotope ratio and lower maturity than that formed in the burial period, belonging to that generated at the early stage of source rock maturity, and is absorbed and stored in coal measure strata. Secondly, physical simulation experiment results at high-temperature and high-salinity inclusions, and almost actual geologic conditions confirm that substantial gas charging and accumulation occurred in the uplift period of the coal measure strata of the two basins. Diffusive flow is the main mode for gas accumulation in the uplift period, which probably reached 56 9 10 12 m 3 in the uplift period of the Xujiahe Formation of the Sichuan Basin, compensating for the diffusive loss of gas in the gas reservoirs, and has an important contribution to the formation of large gas fields. The above insight has promoted the gas resource extent and potential of the coal measure tight sand uplift area; therefore, we need to reassess the areas formerly believed unfavorable where the uplift scale is large, so as to get better resource potential and exploration prospects.

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“…Many methods have been proposed to determine the absolute adsorbed amount from experimental excess isotherms, which always exhibit a maximum including: the linearization method 1,25,26 , the density functional theory via adsorbed volume mapping (AVM) 27 , buoyancy-mediated (BM) 28 methods, a modified Dubinin-Astakhov model 29 , the potential theory for buoyancy effect correction 30 and the fitting of excess isotherm using generalized adsorption isotherm equations [31][32][33] .…”

Section: Introductionmentioning

confidence: 99%