Mass transfer in carbon molecular sieves—an interpretation of Langmuir kinetics

Srinivasan, R.; Auvil, Steven R.; Schork, Joan M.

doi:10.1016/0923-0467(94)02942-3

Cited by 31 publications

(60 citation statements)

References 25 publications

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“…Small molecules experience only a small activation energy for transport through this barrier as is exemplified by carbon dioxide transport in CMS [13]. Experimental studies have shown that the uptake of large molecules has kinetic dependence described by the linear driving force (LDF) model [14][15][16][17][18]. These studies have also shown that intermediately sized molecules can have hybrid uptake kinetics described by a combination of linear driving force and Fickian diffusion models.…”

Section: Introductionmentioning

confidence: 95%

Adsorption equilibrium and transport kinetics for a range of probe gases in Takeda 3A carbon molecular sieve

Rutherford

Coons

2005

Journal of Colloid and Interface Science

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Section: Introductionmentioning

confidence: 95%

Adsorption equilibrium and transport kinetics for a range of probe gases in Takeda 3A carbon molecular sieve

Rutherford

Coons

2005

Journal of Colloid and Interface Science

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“…Table 3 presents the chromatographic data recalculated to determine the separation factors. The retention times for CH 4 were, in general, very long (8-50 minutes) at all investigated temperatures (30-70°C) and on average were 3-4 times longer than for nitrogen (for a particular adsorbent). This ensured very good separation of the chromatographic peaks (Fig.…”

Section: Resultsmentioning

confidence: 97%

“…Values for Q ST available in the literature for N 2, CH 4 and Kr for various carbon-type adsorbents are quite different. However, in many cases, the values fulfil the relation Q ST (N 2 ) < Q ST (CH 4 ) ~ Q ST (Kr).…”

Section: Resultsmentioning

confidence: 99%

“…When the pores of a solid are of a proper size, one may expect that a molecular sieving effect may occur [4]. The molecular sieving effect of a porous solid is more efficient if the gas molecules to be separated are of different dimensions and when the size of the pores is comparable to the dimensions of some of the molecules to be separated.…”

Section: Introductionmentioning

confidence: 99%

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Salix viminaliswood as a new precursor for manufacturing of carbon molecular sieves for effective methane/nitrogen separation

et al. 2015

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Separation of a methane/nitrogen gas mixture was investigated by means of carbon molecular sieves (CMS) obtained from a newly discovered "green" resource: Salix viminalis. This plant grows quickly, yields hard wood and is frequently cultivated for energy purposes (renewable green fuel). Unconventional applications such as charcoal fabrication using this sort of wood are very rare. Carbonization of the wood (1-3 h, 600-700°C) yields carbons with a very narrow pore size distribution (determined by N2 adsorption at -196°C) resembling a perfect CMS. The diameter of most pores (ca. 0.8 nm) is comparable to the size of simple molecules, thus enabling separation. The sieving effect was proven in an industrially important process of CH 4 /N 2 separation at 30-70°C. Despite relatively minor differences of the size of the molecules, the experiment demonstrated that separation factors are placed in the range 3.64-10.20. Additional experiments involving krypton proved that the separation mechanism is based on a geometric factor i.e. the known size and shape of the molecules under separation

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“…Koss et al (1986) showed that the gas behavior in carbons may not be diffusion-limited, therefore it can be accurately modeled using rate expressions. The nonlinear sorption kinetics behavior of gas has previously been studied by several authors, see, for example, Srinivasan et al (1995) and Schlebaum et al (1999). These studies have shown that the nonlinearity can influence diffusive processes.…”

Section: Kinetics Of Gas Sorption In Porous Mediamentioning

confidence: 98%

Mass Transport of Adsorbed-Phase in Stochastic Porous Medium with Fluctuating Porosity Field and Nonlinear Gas Adsorption Kinetics

Fathi

Akkutlu

2011

Transp Porous Med

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Using an upscaling approach based on small perturbation theory, the authors have previously investigated the influence of local heterogeneities in matrix porosity on Darcy flow and Fickian-type pore diffusion in the presence of linear non-equilibrium gas adsorption Fathi and Akkutlu, J. Transp. Porous Med. 80, 281-3044 (2009). They identified non-trivial macro-transport and -kinetics effects of the heterogeneity which significantly retard gas release from the matrix and influence the ultimate gas recovery adversely. The work was a unique fundamental approach for our understanding of gas production and sequestration in unconventional reservoirs; however, it was simplified and did not consider (i) the presence of nonlinear sorption kinetics and (ii) a transport mechanism for the adsorbed phase. In this article, we incorporate the nonlinearity and surface diffusion effects of the adsorbed-phase into their formulation and apply the same upscaling approach to further study the heterogeneity effects. Gas sorption involves the so-called Langmuir kinetics, which is reduced to the well-known Langmuir isotherm in the equilibrium limit. It is found that the nonlinearity participates into both macro-transport and -kinetics, promoting primarily the surface diffusion effects. Whereas surface diffusion, although commonly ignored during modeling subsurface phenomena, brings an intricate nature to the gas release dynamics. Through macro-transport effect of the heterogeneity, it increases ultimate gas recovery and, through the macro-kinetics effect of the heterogeneity, it significantly decreases the time needed to reach the ultimate recovery. As the consequence of these effects, it is shown that the gas-matrix system practically does not reach the equilibrium adsorption limit during any stage of the matrix gas release.

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Mass transfer in carbon molecular sieves—an interpretation of Langmuir kinetics

Cited by 31 publications

References 25 publications

Adsorption equilibrium and transport kinetics for a range of probe gases in Takeda 3A carbon molecular sieve

Adsorption equilibrium and transport kinetics for a range of probe gases in Takeda 3A carbon molecular sieve

Salix viminaliswood as a new precursor for manufacturing of carbon molecular sieves for effective methane/nitrogen separation

Mass Transport of Adsorbed-Phase in Stochastic Porous Medium with Fluctuating Porosity Field and Nonlinear Gas Adsorption Kinetics

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