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Language: English

Conflict of Interest: In relation to this article, we declare that there is no conflict of interest.

Publication history: Received January 13, 2024
Accepted May 6, 2024

This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/bync/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Systematic Narrowing of ZIF-8 Apertures via Controlled 2-Ethylimidazole Doping for Hydrogen/Carbon Dioxide Separation

Lee Yang Sunghwan Park Wong Zhong Han Musab Abdul Razak Lee Yong Zhen Muhammed Faires Rozita Omar Thomas Shean Yeaw Choong Rosiah Rohani Mohamad Rezi Abdul Hamid

Department of Chemical and Environmental Engineering , Universiti Putra Malaysia ¹Department of Energy Chemical Engineering, Department of Advanced Science and Technology Convergence, and Convergence Research Center of Mechanical and Chemical Engineering (CRCMCE) , Kyungpook National University ²Faculty of Engineering and Built Environment , Universiti Kebangsaan Malaysia

Korean Journal of Chemical Engineering, August 2024, 41(8), 2277-2285(9), https://doi.org/10.1007/s11814-024-00192-4

Abstract

Sodalite (SOD) zeolitic-imidazolate frameworks (ZIFs) with uniform angstrom scale apertures can off er high gas sieving

ability for separation applications. Fixed apertures of ZIFs can eff ectively separate specifi c gas pair but may not be able to

provide similar level of separation for larger or smaller gas pairs. Multivariate (i.e., mixed-linker) ZIFs with controlled linker

incorporation can provide desired aperture tuning but diffi cult to synthesize especially when incorporating linkers that would

normally form diff erent structures. Herein, we report a systematic narrowing of SOD ZIF-8 by partially replacing 2-methylimidazole

(mIm) linkers of ZIF-8 with 2-ethylimidazole (eIm) via delayed linker addition (DLA) method. Percentages of

eIm in the hybrid frameworks were determined to be around 14.3%, 9.1%, and 5.1% for ZIF-8 nuclei formed in 5, 12.5, and

20 min, respectively. Ethyl moiety of eIm restricts framework fl exibility of the hybrid ZIF-8, shifts ZIF-8 gate-opening pressure

to higher value, and eventually diminishes the gate-opening eff ect. Polysulfone (PSF)-based mixed-matrix membranes

utilizing eIm-doped ZIF-8 as fi llers displayed slight reduction in CO 2 permeability (18.56 Barrer to 14.85 Barrer) which

result in H 2 /CO 2 ideal selectivity improvement. DLA method is expected to work well for other imidazole-based linkers and

can perhaps be used to synthesize mixed-linker of other SOD ZIFs.

Keywords

Metal–organic frameworks · Zeolitic-imidazole frameworks · Hybrid ZIFs · Mixed-matrix membranes · Gas separations