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

Abstract

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...

Nanocomposite MFI-alumina and FAU-alumina Membranes: Synthesis, Characterization and Application to Paraffin Separation and CO2Capture

“…Nanocomposite MFI-alumina membranes have shown their potentials in several gas and vapour separations (e.g., xylene isomer separation [25,26] and ammonia recovery [27]), and combined with a catalyst in membrane reactors (e.g., i-butane dehydrogenation [28,29] and xylene isomerization [25]). Besides, this nanocomposite configuration has also been applied to the synthesis of other membrane materials, such as Pd-ceramic [30] and MCM-41 ("LUS")-alumina [31] membranes, these latter showing high membrane quality together with high gas and water permeation performance and high structural stability.…”

Xylene isomerization in an extractor type catalytic membrane reactor

“…With an increase in temperature the coverage decreases, and is counterbalanced by the increase of the diffusion coefficient up to a certain point, leading to a further global decrease in permeance, as observed for all gases previously studied on this type of membrane [18][19][20][21][22].…”

Inorganic microporous membranes for H2 and CO2 separation—Review of experimental and modeling progress

“…Nevertheless, the studies on nanocomposite MFI-alumina membranes reveal a monotonic decrease of flux with the increase of temperature, which can be explained by pure surface diffusion without an additional "activated diffusion" mechanism (Miachon et al, 2007;Ciavarella et al, 2000). The authors attribute the flux increase in film-like zeolite membranes to the reversible opening of intercrystalline pathways upon heating, based on their investigation through a simple geometric model.…”

“…b. negligible interactions between the molecules passing through silica pores. It was reported that the gas permeations (i.e., He, Ar, H 2 , N 2 , O 2 , CO, and C 2 H 4 ) through amorphous silica membranes show a predominant increasing trend with the increase of temperature (Smart et al, 2012;Miachon et al, 2007;Nishiyama et al, 1997;Ciavarella et al, 2000;Bai et al, 1995), leading to positive activation energy (Table 2). Exceptionally, the permeation of some large-sized gases such as CO 2 often shows a decreasing trend or a maximum with the increase of temperature, i.e., obviously adsorption-based transport.…”