The Kinetics of Molecular Sieve Action. Sorption of Nitrogen–methane Mixtures by Linde Molecular Sieve 4a

Habgood, H. W.

doi:10.1139/v58-204

Cited by 207 publications

(127 citation statements)

References 17 publications

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“…Transition state theory (eq. 2) therefore predicts that the values of D, for the diffusion of a given molecule in the 4A and 5A zeolites should be essentially the same and that the observed difference in diffusivity should be attributable to a difference in the diffusional 'Data of Habgood (19). tData of Kondis and Dranoff (20).…”

Section: Comparison Of D~flusiuities For 4 a And 5amentioning

confidence: 96%

Diffusion of Light Hydrocarbons in 5A Zeolite

Ruthven¹,

Derrah²,

Loughlin³

1973

Can. J. Chem.

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Experimental diffusivity data are presented for the diffusion of ethane, ethylene, propane, propylene, cyclopropane, n-butane, 1-butene, cis-2-butene, and trtms-2-butene in Linde 5A zeolite. It is shown that the concentration dependence of the diffusivity may be accounted for by considering the non-linearity of the eq~lilibri~~ni isotherms. Activation energies for diffusion, derived from the temperature dependence of the limiting diffusivity at zero sorbate concentration, show a clear correlation with the critical diameters of the sorbate molecules. The data are interpreted in terms of the transition state theory of diffusion and it is shown that, for the simpler molecules, this theory gives a quantitative!^ correct prediction of the pre-exponential factor governing the temperature dependence of the zeolitic diffusivity.Les donnees experimentales de diffi~sion a travers la zeolite Linde 5A ont CtC prbentkes pour ['ethane ethylene, propane, propylene, cyclopropane, n-butane, butene-1, cis butene-2 et trurrs butene-2. 11 a etC possible de tenir compte de la dipendance entre la diffusion et la concentration en considerant des equilibres isothermes non lineaires. Les energies d'activation de diffusion, derivees a partir d e la fonction diffusion limite-temperature pour une concentration nulle de sorbat, montrent une correlation claire avec les diametres critiques des molecules de sorbat. Les donnees ont ete interpretees par rapport a la theorie de I'etat de transition de diffusion et on a montre que pour des molecules simples, cette theorie conduit a une bonne prevision quantitative du facteur prkexponentiel gouvernant la diffusion ziolitique en fonction de la tenipkrature.[Traduit par le journal]Can. J. Chern.. 51, 3514 (1973) The kinetics of sorption of hydrocarbons in molecular sieve zeolites have been widely studied but there are, as yet, few systems for which the dependence of the zeolitic diffusivity on sorbate concentration, temperature and molecular geometry has been clearly established (1). T o obtain such information requires experimental data over a wide range of conditions since, with currently available experimental techniques, the inherent errors can easily conceal the real physical effects. In this laboratory we have used a gravimetric method t o measure the diffusivities of several light hydrocarbons in Linde 5A zeolite and the data from these studies (2-4) are analyzed and interpreted in this paper. The diffusivities for each sorbate show regular trends with concentration and temperature and the effect of molecular size is clearly evident. For the simpler molecules, diffusivities predicted theoretically from transition state theory show good agreement with the experimental data. Experimental

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Section: Comparison Of D~flusiuities For 4 a And 5amentioning

confidence: 96%

Diffusion of Light Hydrocarbons in 5A Zeolite

Ruthven¹,

Derrah²,

Loughlin³

1973

Can. J. Chem.

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“…The "kinetic processes" were recognized soon [28]. In fact, materials like zeolites are called "molecular sieves" because of this effect [136].…”

Section: The Role Of the Adsorbent In Psamentioning

confidence: 99%

“…Information about the adsorption equilibrium of the different species is vital to design and model adsorption processes [19][20][21][22][23][24][25][26][27]. The time required to achieve the equilibrium state may be also important, particularly when the size of the pores of the adsorbent are close to the size of the molecules to be separated [28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43].…”

Section: Introductionmentioning

confidence: 99%

Advances in Pressure Swing Adsorption for Gas Separation

Grande

2012

ISRN Chemical Engineering

184

108

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Pressure swing adsorption (PSA) is a well-established gas separation technique in air separation, gas drying, and hydrogen purification separation. Recently, PSA technology has been applied in other areas like methane purification from natural and biogas and has a tremendous potential to expand its utilization. It is known that the adsorbent material employed in a PSA process is extremely important in defining its properties, but it has also been demonstrated that process engineering can improve the performance of PSA units significantly. This paper aims to provide an overview of the fundamentals of PSA process while focusing specifically on different innovative engineering approaches that contributed to continuous improvement of PSA performance.

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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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The Kinetics of Molecular Sieve Action. Sorption of Nitrogen–methane Mixtures by Linde Molecular Sieve 4a

Cited by 207 publications

References 17 publications

Diffusion of Light Hydrocarbons in 5A Zeolite

Diffusion of Light Hydrocarbons in 5A Zeolite

Advances in Pressure Swing Adsorption for Gas Separation

Carbon Molecular Sieves for Hydrocarbon Separations by Adsorption

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