Chemical cross-linking modification of 6FDA-2,6-DAT hollow fiber membranes for natural gas separation

Chun Cao, Tai-Shung Chung*, Ye Liu, Rong Wang, K. P. Pramoda

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

105 Scopus citations

Abstract

A simple and practical chemical cross-linking method has been demonstrated to make 6FDA-2,6-DAT asymmetric hollow fibers more resistant to plasticization by immersing them into a p-xylenediamine or m-xylenediamine/methanol solution for a short period of time at ambient temperature. FTIR spectra confirm that chemical cross-linking reactions take place between xylenediamine and imide groups of 6FDA-2,6-DAT and form amide groups. The effects of cross-linking modifications on gas separation performance and the resistance to plasticization characteristics are examined by using both pure and CO2/CH4 mixed gas tests. Permeances of all gases tested decrease with an increase in the degree of cross-linking, while CO2/CH4 permselectivity varies in a narrow range. 6FDA-2,6-DAT hollow fibers show favorable resistance to plasticization once the cross-linking reaches a certain degree. XRD spectra indicate almost no changes on the average intersegmental distance of polymer chains after cross-linking modifications, strongly indicating the cross-linking modifications likely protect nodule integrity from CO2-induced swelling and restrict polymer chain vibration for diffusion jumps. In addition, we found that m-xylenediamine has a similar cross-linking effectiveness as p-xylenediamine on 6FDA-2,6-DAT hollow fibers, both yield hollow fiber membranes with comparable CO2/CH4 selectivity and permeance.

Original languageEnglish (US)
Pages (from-to)257-268
Number of pages12
JournalJournal of Membrane Science
Volume216
Issue number1-2
DOIs
StatePublished - May 1 2003

Keywords

  • 6FDA-2,6-DAT polyimide
  • Cross-linking modification
  • Hollow fiber membranes
  • Natural gas separation
  • Plasticization
  • Xylenediamine

ASJC Scopus subject areas

  • Biochemistry
  • Materials Science(all)
  • Physical and Theoretical Chemistry
  • Filtration and Separation

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