Chemical fixation of carbon dioxide catalyzed via covalent triazine frameworks as metal free heterogeneous catalysts without a cocatalyst

Abstract

The synthesis of cyclic carbonates from the catalytic coupling of carbon dioxide (CO₂) and epoxides is regarded as an efficient approach for the production of important industrial feedstock through the chemical fixation of CO₂. However, most of the existing catalysts for this reaction are commonly existing on noble metal sites, and toxic co-catalysts and harsh reaction conditions are ineluctable. Herein, a set of new metal-free covalent triazine frameworks (2,5-DCP-CTF) was synthesized by the trimerization of 2,5-dicyanopyridine (2,5-DCP) exhibiting a hierarchical porous structure and high nitrogen content. In the absence of any co-catalyst and solvent, excellent catalytic activities for the conversion of CO₂ to cyclic carbonates were achieved under mild conditions, and the best conversion rate and selectivity were 99.1% and 95.5%, respectively. This new CTF material can be a more environmentally friendly catalyst for the preparation of cyclic carbonates by the chemical fixation of carbon dioxide.