Team of Prof. Zhongming Liu and Yunpeng Xu from Dalian Institute of Chemical Physics reported a strategy of introducing ZIF fragments into traditional mordenite (MOR) zeolite to decorate the 12-membered ring of MOR. After decoration, the originally ineffectual zeolite MOR exhibited high kinetic propene/propane selectivities and achieved efficient propene/propane separation.
Propene/propane separation is a significant process in chemical industry. However, propene/propane separation has always been a challenging endeavor due to the very small variance in molecular sizes, boiling points and condensabilities between these molecules.
Previously, the research team found that by introducing ZIF subunits into traditional FAU and MFI type zeolites, a series of adsorbents with high CH4/N2selectivities have been synthesized successfully (Angew. Chem. Int. Ed.2019,58, 10241). In this work, the 12-membered ring (12-MR) of MOR was directionally decorated by ZIF fragments, which anchored the imidazoles inside the zeolite pores by taking advantage of the strong covalent binding between Zn2+and imidazole groups.The introduction of the three different fragments resulted in different degrees of 12-MR decoration, and the diffusion of propene and propane molecules wasgreatly affected; the adsorption amount of propene remained constant or even slightly increased, whereas the adsorption amount of propane decreased dramatically. Thus, the originallyineffectual MOR showed great separation performance towards propene/propane. The kinetic propene/propane selectivity of the decorated MOR reached 139 at 25 °C.The propene/propane separation potentials of the resulting adsorbents were further confirmed by breakthrough experiments with equimolar propene/propane (50/50) mixtures.Moreover, propene and propane uptake of the HMOR-eIM that had undergone direct ion-exchange with imidazole decreased simultaneously, showing no efficient performance of propene/propane separation, which further verified the superiority of the strategy of using the strong interaction between zinc cations and imidazole ligands to selectively anchor imidazole in the interior of MOR framework.
This work was published on AngewandteChemie International Edition as hot paper (https://onlinelibrary.wiley.com/doi/10.1002/anie.202000029).
The work was supported by the National Key Research and Development Program of China (2016YFB0301603). (Text by Yaqi Wu)
Enhanced Propene/Propane Separation by Directional Decoration of the 12‐Membered Rings of Mordenite with ZIF Fragments. Yaqi Wu, Shu Zeng, Danhua Yuan, Jiacheng Xing, Hanbang Liu, Shutao Xu, Yingxu Wei, Yunpeng Xu*, Zhongmin Liu*, Angewandte Chemie, 59(17):6765-6768, 2020.
