Postsynthetic Modification of ZIF-8 Membranes via Membrane Surface Ligand Exchange for Light Hydrocarbon Gas Separation Enhancement

Joshua B. James, Lin Lang, Lie Meng, Jerry Y.S. Lin

Research output: Contribution to journalArticlepeer-review

3 Scopus citations

Abstract

The ability to tailor the pore structure of metal-organic framework (MOF) membranes enables synthesis of new or modified MOF membranes with enhanced separation characteristics. This work employs a modified version of solvent-assisted ligand exchange, termed membrane surface ligand exchange (MSLE), to modify the pore structure of zeolitic imidazolate framework-8 (ZIF-8) membranes. This paper is the first to perform a time-based, ex situ characterization and gas permeation study of ZIF-8 MSLE with 5,6-DBIM (DBIM, dimethylbenzimidazole) to effectively narrow the ZIF-8 pores, enhance light hydrocarbon gas-phase separations, and give insight into the exchange mechanism with respect to time and temperature. The results show that relatively fast exchange kinetics occur mainly at the outer surface of the ZIF-8 membrane during the initial 30 min of exchange and enables significant (40-70%) increases in propylene/propane selectivity with minimal (10-20%) propylene permeance losses for the modified ZIF-8 membranes. We postulate as the reaction time proceeds, the ligand-exchange rate slows as the DBIM linker diffuses into the ZIF-8 membrane beyond the external surface, exchanges with the original linker, disrupts the original framework's crystallinity, and then increases long-range order/crystallinity as the reaction proceeds. The H2/C2 separation factor increases with increased 5,6-DBIM content in the ZIF-8 framework which is facilitated by increased MSLE time and reaction temperature.

Original languageEnglish (US)
Pages (from-to)3893-3902
Number of pages10
JournalACS Applied Materials and Interfaces
Volume12
Issue number3
DOIs
StatePublished - Jan 22 2020

Keywords

  • gas separation
  • ligand-exchange modification
  • MOF membranes
  • propane-propylene separation
  • ZIF-8 membranes

ASJC Scopus subject areas

  • Materials Science(all)

Fingerprint Dive into the research topics of 'Postsynthetic Modification of ZIF-8 Membranes via Membrane Surface Ligand Exchange for Light Hydrocarbon Gas Separation Enhancement'. Together they form a unique fingerprint.

Cite this