Studies on the Transition Behavior of Physical Adsorption from the Sub- to the Supercritical Region: Experiments on Silica Gel

Zhou, Li; Zhou, Yaping; Bai, Shupei; Yang, Bin

doi:10.1006/jcis.2002.8542

Cited by 25 publications

(20 citation statements)

References 16 publications

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“…This result may be representative of the differing interactions of methane with shale versus nitrogen and methane with silica gel, or may indicate that additional higher pore pressure data points are required for complete representation of the experimental isotherm. Given the geometry of the Langmuir isotherm purported by Vermylen (2011), a maximum adsorption state can be observed in the supercritical regime ( Figure 5) fulfilling the second caveat of Zhou et al (2002). Subsequently, in this study, the process of accounting for adsorption discussed in Figure 4 is not modified in the supercritical regime.…”

Section: Consideration Of Critical Pressuresupporting

confidence: 55%

“…It has been noted by Zhou et al (2002), among others, that supercritical adsorption will continue at pore pressures greater than the critical pressure for nitrogen and methane adsorbing onto silica gel. Zhou et al (2002) do add the caveats that they detect a transition in adsorption mechanism across the critical transition (a change in the isotherm structure) and that an upper limit exists for supercritical absorption. The experimental results of Vermylen (2011) are collected up to ∼10 MPa, in excess of the critical pressure of methane, but show no deviation from a type I (Langmuir) isotherm upon becoming supercritical.…”

Section: Consideration Of Critical Pressurementioning

confidence: 99%

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The effect of adsorption and Knudsen diffusion on the steady-state permeability of microporous rocks

Allan

Mavko

2013

GEOPHYSICS

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Microporous rocks are being increasingly researched as novel exploration and development technologies facilitate production of the reserves confined in the low-permeability reservoir. The ability to numerically estimate effective permeability is pivotal to characterizing the production capability of microporous reservoirs. In this study, a novel methodology is presented for estimating the steady-state effective permeability from FIB-SEM volumes. We quantify the effect of a static adsorbed monolayer and Knudsen diffusion on effective permeability as a function of pore pressure to better model production of microporous rock volumes. The adsorbed layer is incorporated by generating an effective pore geometry with a pore pressure-dependent layer of immobile voxels at the fluid-solid interface. Due to the steadystate nature of this study, surface diffusion within the adsorbed layer and topological variations of the layer within pores are neglected, potentially resulting in underestimation of effective permeability over extended production time periods. Knudsen diffusion and gas slippage is incorporated through computation of an apparent permeability that accounts for the rarefaction of the pore fluid. We determine that at syn-production pore pressures, permeability varies significantly as a function of the phase of the pore fluid. Simulation of methane transport in micropores indicates that, in the supercritical regime, the effect of Knudsen diffusion relative to adsorption is significantly reduced resulting in effective permeability values up to 10 nanodarcies (9.87 × 10 −21 m 2) less or 40% lower than the continuum prediction. Contrastingly, at subcritical pore pressures, the effective permeability is significantly greater than the continuum prediction due to rarefaction of the gas and the onset of Knudsen diffusion. For example, at 1 MPa, the effective permeability of the kerogen body is five times the continuum prediction. This study demonstrates the importance of, and provides a novel methodology for, incorporating noncontinuum effects in the estimation of the transport properties of microporous rocks.

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Section: Consideration Of Critical Pressuresupporting

confidence: 55%

Section: Consideration Of Critical Pressurementioning

confidence: 99%

The effect of adsorption and Knudsen diffusion on the steady-state permeability of microporous rocks

Allan

Mavko

2013

GEOPHYSICS

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“…The upper limit is the saturation pressure below the critical temperature. The upper limit still exists for supercritical adsorption, although the saturation pressure disappears above the critical temperature [27] . As a fact, adsorption is a phenomenon due to internal force, i.e.…”

Section: Disputation About the Monolayer Mechanismmentioning

confidence: 96%

Impact of supercritical adsorption mechanism on research of hydrogen carrier

Sun

Zhou

et al. 2007

Chin. Sci. Bull.

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Hydrogen storage receives the worldwide attention due to its importance in sustainable energy and the solution of greenhouse effect. Adsorption provides an efficient way to compress gases and, therefore, has been applied to the development of hydrogen storage technology. However, hydrogen is a supercritical gas at the temperature of engineering interest and follows a different adsorption mechanism compared to the sub-critical gases. The present work shows why only monolayer coverage mechanism functions at above-critical temperatures and what consequences will result in the application study. Although there are pros and cons to this point of view, understanding the adsorption mechanism is, indeed, essential for the research of hydrogen storage method since it claims that any storage material based on adsorption will not satisfy the practical need of on board storage no matter how novel the material is.supercritical adsorption, mechanism, impact, hydrogen storage

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“…0.7 to 2 nm wide [5]) does not contribute to v a i once they are able to accommodate more than two adsorbate molecules in width. The situation is still different in the critical temperature region, where a multilayer was shown to take place under high pressure [39,40]. Furthermore, in case the adsorbent is not exclusively microporous (e.g.…”

Section: Assessing the Amount Adsorbedmentioning

confidence: 99%

Surface excess amounts in high-pressure gas adsorption: Issues and benefits

Rouquérol

Llewellyn

et al. 2016

Colloids and Surfaces A: Physicochemical and Engineering Aspect

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International audienceThis paper introduces a calculation procedure aimed at improving the accuracy and meaningfulness of high-pressure gas adsorption data obtained by either adsorption manometry or gravimetry. The procedure is based on the Gibbs model and avoids the usual simplifying assumption that the well-defined Gibbs Dividing Surface (the GDS) coincides with the ill-defined adsorptive-accessible surface of the microporous adsorbent. Instead, it makes a clear distinction between the two surfaces and introduces the concept of “Gibbs exclusion volume” (i.e. the volume enclosed by the GDS) which is shown to be central in the calculation of the surface excess amount and useful to avoid any confusion with the adsorbent volume. It is shown, in the case of methane adsorption on gas shale, how this procedure avoids introducing the uncertainty due to the dead volume determination in an inter-laboratory comparison. The conditions for a surface excess isotherm to be a useful intermediate step in the assessment of the amount adsorbed are stressed and illustrated

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Studies on the Transition Behavior of Physical Adsorption from the Sub- to the Supercritical Region: Experiments on Silica Gel

Cited by 25 publications

References 16 publications

The effect of adsorption and Knudsen diffusion on the steady-state permeability of microporous rocks

The effect of adsorption and Knudsen diffusion on the steady-state permeability of microporous rocks

Impact of supercritical adsorption mechanism on research of hydrogen carrier

Surface excess amounts in high-pressure gas adsorption: Issues and benefits

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