Leaching in Specific Facets of ZIF-67 and ZIF-L Zeolitic Imidazolate Frameworks During the CO₂ Cycloaddition with Epichlorohydrin

Abstract

Zeolitic imidazolate frameworks (ZIFs) have been profusely used as catalysts for inserting CO 2 into organic epoxides (i.e., epichlorohydrin) through cycloaddition. Here, we demonstrate that these materials suffer from irreversible degradation by leaching. To prove this, we performed the reactions and analyzed the final reaction mixtures by elemental analysis and the resulting materials by different microscopies. We found that the difference in catalytic activity between three ZIF-67 and one ZIF-L catalysts was related to the rate at which the materials degraded. Particularly, the {100} facet leaches faster than the others, regardless of the material used. The catalytic activity strongly depended on the amount of leached elements in the liquid phase since these species are extremely active. Our work points to the instability of these materials under relevant reaction conditions and the necessity of additional treatments to improve their stability.

Harnessing nanoscale spatial effects in inner-modified zeolitic imidazolate framework-8 for enhanced Knoevenagel condensation reaction

“…The manipulation of MOF structures, encompassing aspects like crystal size, [17][18][19] facet orientation, [20][21][22] functional group incorporation [23][24][25] and composition, [26][27][28] has been undertaken to discern the intricate interplay between their structures and catalytic performance. Zeolitic imidazolate frameworks (ZIFs) can be regarded as prototypical MOFs due to their large library of zeolite-like crystalline topologies (comprising over 150 structures) and facile aqueous-based synthesis, which allows for adaptation of various functional groups and production of colloidal crystals with controlled size and morphology.…”

Experimental and Theoretical Investigation of Interfacial Engineering in Fe2O3/NiFe2O4 Heterostructures toward the Cycloaddition of CO2 with Styrene Oxide

“…The ever-increasing global CO 2 emission due to the massive use of fossil fuels has disrupted the carbon balance, raising worldwide concerns about global warming, climate change, and aggravating environmental issues. Although the CO 2 capture and storage technology can reduce the CO 2 concentration in the atmosphere, the chemical utilization of CO 2 as a molecular C 1 synthon for the production of value-added chemicals is more appealing for achieving the goal of carbon neutrality and sustainable carbon recycling. − Several strategies have been proposed for the effective conversion of CO 2 , such as electrochemical CO 2 reduction, photocatalytic CO 2 transformation, catalytic hydrogenation of CO 2 , biochemical conversion of CO 2 , CO 2 reductive amination, and cycloaddition of CO 2 with epoxides. − Among the promising routes in CO 2 catalysis, the chemical fixation of CO 2 into epoxides for the synthesis of cyclic carbonates with a 100% atom efficiency is a vibrant research area. Cyclic carbonates, such as ethylene carbonate, propylene carbonate, and SC, are important aprotic solvents, electrolytes for lithium batteries, polymer precursors, and organic building blocks. − For example, SC can be generated by the cycloaddition reaction between CO 2 and SO via the ring-opening of SO, insertion of CO 2 , and intramolecular cyclization .…”

Impact of exposed crystal facets on oxygen reduction reaction activity in zeolitic imidazole frameworks

“…In addition, the different exposed crystallographic planes or facets in ZIF-67 were studied to improve the reactivity of CO 2 cycloaddition. 23 However, the tuning of the morphology and crystal facets in pristine ZIF-67 to improve the ORR activity has never been reported so far.…”