Inverse CO2/C2H2 Separation with MFU-4 and Selectivity Reversal via Postsynthetic Ligand Exchange

Qiao Liu, Sung Gu Cho, Jordon Hilliard, Ting Yuan Wang, Szu Chia Chien, Li Chiang Lin, Anne C. Co, Casey R. Wade

Research output: Contribution to journalArticlepeer-review

7 Scopus citations

Abstract

Although many porous materials, including metal–organic frameworks (MOFs), have been reported to selectively adsorb C2H2 in C2H2/CO2 separation processes, CO2-selective sorbents are much less common. Here, we report the remarkable performance of MFU-4 (Zn5Cl4(bbta)3, bbta=benzo-1,2,4,5-bistriazolate) toward inverse CO2/C2H2 separation. The MOF facilitates kinetic separation of CO2 from C2H2, enabling the generation of high purity C2H2 (>98 %) with good productivity in dynamic breakthrough experiments. Adsorption kinetics measurements and computational studies show C2H2 is excluded from MFU-4 by narrow pore windows formed by Zn−Cl groups. Postsynthetic F/Cl ligand exchange was used to synthesize an analogue (MFU-4-F) with expanded pore apertures, resulting in equilibrium C2H2/CO2 separation with reversed selectivity compared to MFU-4. MFU-4-F also exhibits a remarkably high C2H2 adsorption capacity (6.7 mmol g−1), allowing fuel grade C2H2 (98 % purity) to be harvested from C2H2/CO2 mixtures by room temperature desorption.

Original languageEnglish
Article numbere202218854
JournalAngewandte Chemie - International Edition
Volume62
Issue number18
DOIs
StatePublished - 24 Apr 2023

Keywords

  • Acetylene
  • CO
  • Inverse Separation
  • Metal–Organic Frameworks
  • Molecular Sieving

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