CO2 fixation for the synthesis of cyclic carbonates using Br-ZIF-L with enriched defects

Abstract

Zeolitic imidazolate frameworks (ZIFs) are rich in accessible and active Lewis acid-base sites and hierarchical pores, making them effective catalysts for the cycloaddition of CO₂ to epoxides under mild conditions. In this study, a facile defect-engineering strategy using acid etching and ligand exchange was developed to convert three-dimensional ZIF-L into layered Br-ZIF-L with a tire-like surface, abundant active sites, and a structure optimized for efficient mass diffusion. This modification enabled the rapid cycloaddition of CO₂ to propylene oxide under mild conditions (1 MPa and 100 °C for 2 h). The resulting cyclic carbonate was obtained in 92 % yield and 100 % selectivity. Additionally, Br-ZIF-L exhibited excellent chemical stability without a loss of catalytic activity after six consecutive cycles, highlighting its potential as a high-performance catalyst for CO₂ conversion. The developed catalytic system exhibited a conversion rate of >90 % for five different substituted epoxides. This study introduces an efficient approach for synthesizing cyclic carbonates via CO₂ fixation under mild conditions.