Revisiting Transport of Gases in the Micropores of Carbon Molecular Sieves

Huang, Qinglin; Sundaram, Sudha; Farooq, Shamsuzzaman

doi:10.1021/la026451+

Cited by 77 publications

(99 citation statements)

References 19 publications

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“…A successful description of the transport mechanism is the dual resistance model, in which the transport is controlled by a barrier resistance at the mouth of the micropores followed by diffusion in its interior. 7,21,22,24,38 The barrier resistance is based on the fact that CMS preparation involves a cracking process, which results in the narrowing of the micropore openings. 28,38,39 In this work we have used the dual resistance model.…”

Section: Adsorption Kineticsmentioning

confidence: 99%

Adsorption Equilibrium and Kinetics of Methane and Nitrogen on Carbon Molecular Sieve

Yang

Ribeiro

et al. 2014

Ind. Eng. Chem. Res.

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Knowledge of adsorption equilibrium and kinetic data is essential for the design of an adsorption process. In this work, the adsorption equilibrium isotherms of methane and nitrogen are reported at 303, 323, and 343 K over the pressure range from 0 to 700 kPa by a gravimetric system on a carbon molecular sieve (CMS-131510). Methane is preferentially adsorbed. The adsorption capacity at 303 K and 700 kPa is 1.91 mol/kg for methane and 1.01 mol/kg for nitrogen. Experimental data obtained were fitted with the multisite Langmuir model and Toth model. The adsorption kinetics of pure gas was studied by a batch uptake experiment at several different surface coverages within the pressure range of 0−100 kPa and in the same temperature range covered by the equilibrium isotherm. The adsorption rate of both gases is found to be controlled by the surface barrier resistance at the mouth of the micropore and diffusion in the micropore interior. The dual resistance model employed in the simulation can successfully describe the uptake curves. The temperature and concentration dependences of kinetic parameters were also studied. A very high kinetic selectivity was observed. The effect of micropore distribution on the transport parameters is discussed in detail. Binary breakthrough curves were determined, and an enrichment of 50% for methane in the first few seconds was observed. The data reported in this work can be used for the future modeling of adsorption process for the separation of methane and nitrogen on this CMS material.

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Section: Adsorption Kineticsmentioning

confidence: 99%

Adsorption Equilibrium and Kinetics of Methane and Nitrogen on Carbon Molecular Sieve

Yang

Ribeiro

et al. 2014

Ind. Eng. Chem. Res.

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“…Subsequently, some studies have resurrected the Schneider and Smith [26] approach, considering particle scale diffusion in the micropores with negligible transport resistance at the microscale, but with a nonlinear isotherm and finite mass exchange rate between macropores and micropores [36][37][38]. In other work, Loughlin et al [39], Qinglin et al [40,41] and Wang and LeVan [42] have considered a surface barrier resistance in series with a micropore diffusion resistance for the diffusion of gases in carbon molecular sieves, with negligible direct contribution of micropores to the macroscale flux.…”

Section: Introductionmentioning

confidence: 99%

Slow diffusion of methane in ultra-micropores of silicon carbide-derived carbon

Shahtalebi

Farmahini

Shukla

et al. 2014

Carbon

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“…This separation is practiced by cryogenic distillation when large flowrates are available and helium can be obtained as a byproduct. In this topic much of the literature was also concerned with adsorbent characterization [3,5,[9][10][11] but more works can be found specifically on PSA processes using carbon molecular sieves [12][13]. In these works, poor purity was obtained because the feed has high nitrogen molar fractions (>40%) for landfill gas applications.…”

Section: Introductionmentioning

confidence: 99%

Carbon Molecular Sieves for Hydrocarbon Separations by Adsorption

Grande

Cavenati

Silva

et al. 2005

Ind. Eng. Chem. Res.

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The use of vacuum pressure swing adsorption (VSA-PSA) with carbon molecular sieves (CMS) as selective sorbents is evaluated as an alternative technology for methane−nitrogen and propane−propylene separations. The larger molecules, methane and propane, are very low-diffusing species, resulting in processes where nitrogen and propylene are retained in the bed. For the methane−nitrogen separation, a Skarstrom cycle (pressurization, feed, blowdown, and purge) was used with the advantage of recovering methane in the feed step with a low-pressure drop. At ambient temperature, from a mixture with 20% of nitrogen balanced by methane, a purity >93% was obtained. For the propane−propylene mixture, a five-step cycle was usedpressurization, feed, rinse, intermediate depressurization, and countercurrent blowdownwhere purified propylene is obtained as a low-pressure product. Starting with an equimolar mixture at 373 K, the purity of propylene was 83% with a product recovery of 84%.

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Revisiting Transport of Gases in the Micropores of Carbon Molecular Sieves

Cited by 77 publications

References 19 publications

Adsorption Equilibrium and Kinetics of Methane and Nitrogen on Carbon Molecular Sieve

Adsorption Equilibrium and Kinetics of Methane and Nitrogen on Carbon Molecular Sieve

Slow diffusion of methane in ultra-micropores of silicon carbide-derived carbon

Carbon Molecular Sieves for Hydrocarbon Separations by Adsorption

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