ZIF‐8 Membrane Separation Performance Tuning by Vapor Phase Ligand Treatment

• Published in: Angewandte Chemie Vol. 131; no. 46; pp. 16542 - 16546
• Main Authors: Eum, Kiwon, Hayashi, Mikio, De Mello, Matheus Dorneles, Xue, Feng, Kwon, Hyuk Taek, Tsapatsis, Michael
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 11.11.2019; Wiley Blackwell (John Wiley & Sons)
• Subjects: Air separation; Air temperature; Ambient temperature; Aminobenzimidazole; Carbon dioxide; Chemistry; Dampfphase; Ligandinduzierte Permselektivität; Ligands; Membrane separation; Membranen; Membranes; Metall-organische Gerüste; Methane; Oxygen; Selectivity; Thickness; Vapor phases; Vapors; ZIF-8
• ISSN: 0044-8249; 1521-3757
• DOI: 10.1002/ange.201909490

Vapor phase ligand treatment (VPLT) of 2‐aminobenzimidazole (2abIm) for 2‐methylimidazole (2mIm) in ZIF‐8 membranes prepared by two different methods (LIPS: ligand induced permselectivation and RTD: rapid thermal deposition) results in a notable shift of the molecular level cut‐off to smaller molecules establishing selectivity improvements from ca. 1.8 to 5 for O2/N2; 2.2 to 32 for CO2/CH4; 2.4 to 24 for CO2/N2; 4.8 to 140 for H2/CH4 and 5.2 to 126 for H2/N2. Stable (based on a one‐week test) oxygen‐selective air separation performance at ambient temperature, 7 bar(a) feed, and 1 bar(a) sweep‐free permeate with a mixture separation factor of 4.5 and oxygen flux of 2.6×10−3 mol m−2 s−1 is established. LIPS and RTD membranes exhibit fast and gradual evolution upon a 2abIm‐VPLT, respectively, reflecting differences in their thickness and microstructure. Functional reversibility is demonstrated by showing that the original permeation properties of the VPLT‐LIPS membranes can be recovered upon 2mIm‐VPLT. Die Abtrennung von Sauerstoff aus der Luft und andere Gastrennungen werden ermöglicht, indem ZIF‐Membranen durch einfache Dampfphasen‐Ligandenbehandlung (VPLT) modifiziert werden. Die Veränderungen der Permeationseigenschaften sind reversibel und können schrittweise erfolgen, sodass das Membranverhalten auf die Anwendung zugeschnitten werden kann.