Xylene Vapor Permeation in MFI-Zeolite Membranes Made by Templated and Template-free Secondary Growth of Randomly Oriented Seeds: Effects of Xylene Activity and Microstructure

Fateme Banihashemi, Lie Meng, Ali A. Babaluo, Jerry Lin

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

Many studies have reported high p-xylene/o-xylene perm-selectivities with MFI zeolite membranes, however, these results were obtained at low xylene activity (<0.01). The present work investigates the vapor permeation of xylene isomers through MFI zeolite membranes at various xylene activities up to 0.033. Using MFI zeolite membranes synthesized with and without organic templates, the effects of xylene activity and membrane microstructure on separation performance in xylene vapor permeation were systematically studied. Both p-xylene and o-xylene permeances decrease with increasing xylene activity, but the decrease is more pronounced for p-xylene resulting in a reduction in p-xylene/o-xylene selectivity. The MFI zeolite membrane fabricated without template exhibits higher p-xylene selectivity than the templated membrane due to the less intercrystalline gaps in the template-free zeolite layer, and a less decrease in p-xylene selectivity for templated-free membrane was confirmed with increasing xylene activity. A theoretical study using the transport model for MFI zeolite membrane reveals that the xylene activity dependence of xylene permeance and selectivity could be well explained by the decrease of both xylene solubility and diffusivity in zeolitic pores with increasing xylene activity. Also, the minimization of intercrystalline gaps in zeolite layer weakens the unfavorable xylene activity dependence in xylene vapor separation.

Original languageEnglish (US)
JournalIndustrial and Engineering Chemistry Research
DOIs
StateAccepted/In press - Mar 29 2018

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Zeolites
Xylenes
Xylene
Permeation
Seed
Vapors
Membranes
Microstructure
Isomers
4-xylene

ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)
  • Industrial and Manufacturing Engineering

Cite this

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title = "Xylene Vapor Permeation in MFI-Zeolite Membranes Made by Templated and Template-free Secondary Growth of Randomly Oriented Seeds: Effects of Xylene Activity and Microstructure",
abstract = "Many studies have reported high p-xylene/o-xylene perm-selectivities with MFI zeolite membranes, however, these results were obtained at low xylene activity (<0.01). The present work investigates the vapor permeation of xylene isomers through MFI zeolite membranes at various xylene activities up to 0.033. Using MFI zeolite membranes synthesized with and without organic templates, the effects of xylene activity and membrane microstructure on separation performance in xylene vapor permeation were systematically studied. Both p-xylene and o-xylene permeances decrease with increasing xylene activity, but the decrease is more pronounced for p-xylene resulting in a reduction in p-xylene/o-xylene selectivity. The MFI zeolite membrane fabricated without template exhibits higher p-xylene selectivity than the templated membrane due to the less intercrystalline gaps in the template-free zeolite layer, and a less decrease in p-xylene selectivity for templated-free membrane was confirmed with increasing xylene activity. A theoretical study using the transport model for MFI zeolite membrane reveals that the xylene activity dependence of xylene permeance and selectivity could be well explained by the decrease of both xylene solubility and diffusivity in zeolitic pores with increasing xylene activity. Also, the minimization of intercrystalline gaps in zeolite layer weakens the unfavorable xylene activity dependence in xylene vapor separation.",
author = "Fateme Banihashemi and Lie Meng and Babaluo, {Ali A.} and Jerry Lin",
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AU - Meng, Lie

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AU - Lin, Jerry

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AB - Many studies have reported high p-xylene/o-xylene perm-selectivities with MFI zeolite membranes, however, these results were obtained at low xylene activity (<0.01). The present work investigates the vapor permeation of xylene isomers through MFI zeolite membranes at various xylene activities up to 0.033. Using MFI zeolite membranes synthesized with and without organic templates, the effects of xylene activity and membrane microstructure on separation performance in xylene vapor permeation were systematically studied. Both p-xylene and o-xylene permeances decrease with increasing xylene activity, but the decrease is more pronounced for p-xylene resulting in a reduction in p-xylene/o-xylene selectivity. The MFI zeolite membrane fabricated without template exhibits higher p-xylene selectivity than the templated membrane due to the less intercrystalline gaps in the template-free zeolite layer, and a less decrease in p-xylene selectivity for templated-free membrane was confirmed with increasing xylene activity. A theoretical study using the transport model for MFI zeolite membrane reveals that the xylene activity dependence of xylene permeance and selectivity could be well explained by the decrease of both xylene solubility and diffusivity in zeolitic pores with increasing xylene activity. Also, the minimization of intercrystalline gaps in zeolite layer weakens the unfavorable xylene activity dependence in xylene vapor separation.

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