Highly active and robust [DBUH]Br@PILCOOH catalyst for CO2 cycloaddition: one-pot fabrication via ionic liquid immobilization on poly(ionic liquid)s†

Abstract

Global challenges such as climate change and environmental pollution make the efficient utilization of waste CO₂ emissions increasingly critical. The cycloaddition of CO₂ with epoxides to form cyclic carbonates is an attractive process, integrating waste gas conversion with the production of value-added chemicals. However, the development of catalysts that are both highly efficient and environmentally benign remains a significant challenge. In this study, we report a novel heterogeneous composite ionic liquid catalyst, [DBUH]Br@PILCOOH, featuring a high ionic liquid content synthesized via a simple one-pot process. [DBUH]Br@PILCOOH uniquely combines two types of proton donors acting as Lewis acid centers with a nucleophilic bromide ion (Br⁻) and a mesoporous polyionic liquid framework. This innovative structure results in exceptional catalytic performance, achieving high yields (95.7–98.6%) and excellent selectivities (>99%) across a wide range of epoxides under mild conditions (ambient CO₂ pressure, 80 °C, solvent-free, and without co-catalysts). The synergistic effect of the catalyst's components not only enhances activity but also significantly improves recyclability, maintaining high performance after six cycles with minimal loss of active sites. This represents a substantial advancement over existing catalysts, offering a new avenue for efficient CO₂ utilization. Furthermore, the novel approach for preparing such heterogeneous composite ionic liquid catalysts opens up broader environmental applications, paving the way for scalable and eco-friendly CO₂ conversion technologies.