High-temperature stainless steel supported zeolite (MFI) membranes: Preparation, module construction, and permeation experiments

Geus, E.R.; Bekkum, H. van; Bakker, W.J.W.; Moulijn, Jacob A.

doi:10.1016/0927-6513(93)80019-q

Cited by 190 publications

(80 citation statements)

References 20 publications

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“…28a shows the transient permeation of the CH 4 -nC 4 H 10 mixture across an MFI zeolite membrane. 47 The permeation fluxes are influenced by a combination of adsorption strengths and mobilities. The smaller molecule CH 4 has a mobility of about 100 times higher than that of the bulkier n-butane.…”

Section: View Article Onlinementioning

confidence: 99%

Uphill diffusion in multicomponent mixtures

2015

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Molecular diffusion is an omnipresent phenomena that is important in a wide variety of contexts in chemical, physical, and biological processes. In the majority of cases, the diffusion process can be adequately described by Fick's law that postulates a linear relationship between the flux of any species and its own concentration gradient. Most commonly, a component diffuses down the concentration gradient. The major objective of this review is to highlight a very wide variety of situations that cause the uphill transport of one constituent in the mixture. Uphill diffusion may occur in multicomponent mixtures in which the diffusion flux of any species is strongly coupled to that of its partner species. Such coupling effects often arise from strong thermodynamic non-idealities. For a quantitative description we need to use chemical potential gradients as driving forces. The transport of ionic species in aqueous solutions is coupled with its partner ions because of the electro-neutrality constraints; such constraints may accelerate or decelerate a specific ion. When uphill diffusion occurs, we observe transient overshoots during equilibration; the equilibration process follows serpentine trajectories in composition space. For mixtures of liquids, alloys, ceramics and glasses the serpentine trajectories could cause entry into meta-stable composition zones; such entry could result in phenomena such as spinodal decomposition, spontaneous emulsification, and the Ouzo effect. For distillation of multicomponent mixtures that form azeotropes, uphill diffusion may allow crossing of distillation boundaries that are normally forbidden. For mixture separations with microporous adsorbents, uphill diffusion can cause supra-equilibrium loadings to be achieved during transient uptake within crystals; this allows the possibility of over-riding adsorption equilibrium for achieving difficult separations. Key learning points(1) Coupling effects in mixture diffusion may cause uphill transport of a component (2) Uphill diffusion results in transient overshoots and serpentine equilibration trajectories (3) Non-ideal phase equilibrium thermodynamics is often the major source of diffusional coupling effects (4) Chemical potential gradients are the proper driving forces for diffusion (5) Uphill transport can be exploited to achieve difficult and unusual separations

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Section: View Article Onlinementioning

confidence: 99%

Uphill diffusion in multicomponent mixtures

2015

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“…7 MFI-type zeolite membranes offer potential applications for separation of hydrocarbon isomers. [8][9][10][11] This is due to a dual effect of molecular sieving of permeating gas molecules by the zeolitic pores from size and shape selectivity as well as the preferential adsorption by zeolitic pores governed by the surface chemistry.…”

Section: Introductionmentioning

confidence: 99%

Gas permeation through DDR‐type zeolite membranes at high temperatures

et al. 2008

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in Wiley InterScience (www.interscience.wiley.com).DDR-type zeolite membranes were prepared by the secondary growth method on porous a-alumina disk, followed by on-stream counter diffusion chemical vapor deposition modification to eliminate the intercrystalline micropores. Single gas permeation of He, H 2 , CO 2 , and CO through this zeolite membrane before and after CVD modification was measured in 25-5008C. Intracrystalline diffusivities for these four gases in DDR-type zeolite were obtained from the permeation data above 3008C to examine the effects of the size and molecular weight of permeating gases on diffusion and permeation rate for this zeolite membrane. For the unmodified DDR-type zeolite membrane with presence of a small amount intercrystalline micropores the diffusivity (or permeance) with a low activation energy depends on both the size and molecular weight of permeating gases. For the CVD-modified DDR-type zeolite membrane with intercrystalline micropores eliminated, the activation energy for diffusion and diffusivity increases with increasing molecular size of the permeating gases.

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“…Permselectivity α i /j , of gas i over gas j, was calculated as the ratio of the two pure gas permeances. Separation factor S f was calculated as an enrichment factor in the permeate as compared to the feed composition ratio [30].…”

Section: Permeance Permselectivity and Separation Factormentioning

confidence: 99%

“…Although various models have been proposed for the determination of single gas diffusion [14,[27][28][29][30], the transport in the zeolite pores is still poorly understood.…”

Section: Introductionmentioning

confidence: 99%

Experimental study and numerical simulation of hydrogen/isobutane permeation and separation using MFI-zeolite membrane reactor

et al. 2000

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A composite alumina-MFI-zeolite membrane has been prepared by a pore-plugging method. Transport through this membrane is controlled by molecular size and adsorption properties, as expected for a defect-free zeolite composite layer.Single gas transport was studied for hydrogen and isobutane. In the studied temperature range, (323-723 K) for isobutane and (277-723 K) for hydrogen, transports were activated. Isobutane exhibited a flux maximum at 450 K, whereas hydrogen flux declined with temperature.These different permeation behaviors were modeled using Maxwell-Stefan equations taking into account only surface diffusion. Activation energies were obtained from the model by fitting the experimental data. They were calculated to be 31 kJ mol −1 for isobutane and 1.9 kJ mol −1 for hydrogen. The diffusion coefficients calculated at 323 K differed by four orders of magnitude.Separation experiments with a mixture of hydrogen and isobutane in a 293-723 K temperature range were performed. Typical permeation behavior was observed for a mixture of weakly and strongly adsorbed molecules. At room temperature, hydrogen permeation was hindered by stronger adsorbed isobutane molecules in the micropores. H 2 /i-C 4 H 10 separation experiments showed a separation factor of 25 at 723 K, a typical temperature of the isobutane dehydrogenation in membrane reactors. RésuméUne membrane composite alumine-zéolithe MFI est préparée par une méthode de bouchage de pores. Le transport à travers la membrane est contrôlé par la taille des molécules et leurs propriétés d'adsorption, comme on peut s'y attendre dans une couche composite zéolithique sans défaut.Le transport des gas purs est étudié pour l'hydrogène et l'isobutane. Dans les domaines de température étudiés, 323-723 K pour l'isobutane et 277-723 K pour l'hydogène, le transport de ces deux gaz est activé. Le flux d'isobutane présente un maximum à 450 K, alors que celui d'hydrogène diminue avec la température.Ces différents comportements en perméation sont modélisés en utilisant les équations de Maxwell-Stefan appliquées uniquement à la diffusion de surface. L'ajustement de l'équation du modèle aux données expérimentales permet d'obtenir les energies d'activation de diffusion. Celles-ci sont de 31 kJ mol −1 pour l'isobutane et de 1.9 kJ mol −1 pour l'hydrogène. Les coefficients de diffusion calculés à 323 K sont dans un rapport de 10 4 .Des expériences de séparation hydrogène/isobutane sont effectuées dans une gamme de température de 293 à 723 K. Il a été observé un comportement en perméation typique d'un mélange binaire de molécules gazeuses fortement et faiblement * Corresponding author. Fax: +33-4-7244-5399. E-mail address: dalmon@catalyse.univ-lyon.fr (J.-A. Dalmon).0920-5861/00/$ -see front matter ©2000 Elsevier Science B.V. All rights reserved. PII: S 0 9 2 0 -5 8 6 1 ( 9 9 ) 0 0 2 8 3 -7 254 P. Ciavarella et al. / Catalysis Today 56 (2000) [253][254][255][256][257][258][259][260][261][262][263][264] adsorbées. À température ambiante, la perméation d'hydrogène est gênée pa...

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High-temperature stainless steel supported zeolite (MFI) membranes: Preparation, module construction, and permeation experiments

Cited by 190 publications

References 20 publications

Uphill diffusion in multicomponent mixtures

Uphill diffusion in multicomponent mixtures

Gas permeation through DDR‐type zeolite membranes at high temperatures

Experimental study and numerical simulation of hydrogen/isobutane permeation and separation using MFI-zeolite membrane reactor

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