Structure regulation and catalytic performance of amine-functionalized zeolitic imidazolate frameworks for CO₂ cycloaddition

The capture and transformation of CO₂, utilized as a C1 resource, play an integral role in mitigating CO₂ emissions and addressing the emerging 'carbon source crisis.' The CO₂ cycloaddition to cyclic carbonate is particularly noteworthy. A critical factor in optimizing the efficiency and minimizing the costs associated with CO₂ cycloaddition is the selection of an effective catalyst. A novel amine-functionalized intramolecular acid-base synergistic ZIF catalyst, designated as ABF-ZIF-X, was synthesized using a mixed ligand method, employing 2-MeIM and the larger molecular-sized ligand 2-amBzIM. The introduction of an amino active center and the strategic regulation of the active site defects in metal ions enable ABF-ZIF-X to enhance the density of Lewis acid and base sites. This enhancement facilitates intramolecular acid-base cooperation, which is pivotal for effective CO₂ cycloaddition catalysis. Notably, ABF-ZIF-X exhibits exceptional catalytic activity in the cycloaddition of EBH with CO₂, eliminating the need for additional solvents and co-catalysts. The reaction mechanism of CO₂ cycloaddition, which is intramolecular acid-base synergistic catalysis and bimolecular activation, was proposed. Among the synthesized catalysts. ABF-ZIF-0.15 shows superior performance, achieving an impressive 96.7% conversion of EBH and a selectivity of 97.1%. Furthermore, this catalyst demonstrates remarkable reusability, maintaining high activity across five cycles.