Abstract
In this study, the catalytic activities of three types of zeolitic imidazolate framework-8 (ZIF-8) (two types were synthesized in aqueous and methanolic media, while the other was commercially available) with respect to CO2 cycloaddition to epichlorohydrin were evaluated. Surprisingly, only the ZIF-8 that was synthesized in an aqueous medium showed a marked catalytic performance, leading to the generation of the desired product, chloropropene carbonate. On the contrary, the other two types of ZIF-8 showed little to no catalytic activity. It is conjectured that the water molecules occluded inside the as-synthesized ZIF-8 triggered the dissociation of Zn-N bonds, resulting in a concomitant transformation to a new, dense phase. Accordingly, it is plausible that dissociated Zn or N species were formed during the reaction. In particular, we found that the dissociated N species arising from the dissociation of Zn-N bonds were pyrrolic and pyridinic, while the dissociated Zn species were bound to hydroxyl groups. Finally, complementary interpretation of CO2– and NH3-based temperature-programmed desorption and NH3-adsorbed Fourier transform infrared spectroscopy results revealed that the dissociated Zn species connected with hydroxyl groups, observed only in the ZIF-8 synthesized in an aqueous medium, served simultaneously as Lewis acids and bases and, thus, were crucial to the CO2 cycloaddition reaction.
Original language | English |
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Article number | 134964 |
Journal | Chemical Engineering Journal |
Volume | 435 |
DOIs | |
Publication status | Published - 2022 May 1 |
Bibliographical note
Publisher Copyright:© 2022 The Authors
Keywords
- CO cycloaddition
- CO utilization
- Structural transformation
- Zeolitic imidazolate framework-8
ASJC Scopus subject areas
- General Chemistry
- Environmental Chemistry
- General Chemical Engineering
- Industrial and Manufacturing Engineering