Thermal stability of ZIF-8 membranes for gas separations

Joshua B. James, Jerry Lin

Research output: Contribution to journalArticlepeer-review

31 Scopus citations

Abstract

The thermal stability of ZIF membranes is important for high temperature separation applications but has not been systematically studied. This work highlights the results of a thermal stability study of ZIF-8 membranes in terms of material structure, H2/CO2 gas permeation and separation characteristics. During binary and single gas temperature dependent permeance tests conducted from 25 to 250 °C, both H2 and CO2 permeances decrease as a function of temperature. In the binary test, H2/CO2 selectivity increases between 25 and 225 °C, and then decreases as temperature is further increased between 225–275 °C. The results can be explained by the adsorption/diffusion mechanism. Beyond 275 °C, H2/CO2 permeance and selectivity drastically increase with respect to temperature and is indicative of ZIF-8 membrane partial carbonization during the dynamic 30 h temperature dependent test. The time/temperature dependency of the onset of ZIF-8 thin film structural change was deconvoluted in isothermal transient permeation experiments. Transient tests performed at 50, 100, 150 and 300 °C for 24 h indicate that ZIF-8 thin films maintain their crystallinity and structural integrity below 150 °C. However, at temperatures of 150 °C and greater the framework undergoes increased magnitudes of thermally induced carbonization as a function of temperature. Thermomechanically induced stresses between the ZIF-8 membrane thin film and α–alumina support may account for differences in static thermal stability observed when comparing ZIF-8 membranes and ZIF-8 crystalline powders.

Original languageEnglish (US)
Pages (from-to)9-19
Number of pages11
JournalJournal of Membrane Science
Volume532
DOIs
StatePublished - 2017

Keywords

  • Gas separation
  • High temperature
  • Membrane carbonization
  • Thermal stability
  • ZIF-8 membrane

ASJC Scopus subject areas

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

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