Experimental and theoretical investigation for the cycloaddition of carbon dioxide to epoxides catalyzed by potassium and boron co-doped carbon nitride

Much endeavor has been devoted to efficient heterogeneous catalysts for carbon dioxide (CO2) conversion to high-value chemicals. Meanwhile, the cycloaddition of CO2 to epoxides is considered as a green and atom-economy reaction to produce cyclic carbonates. Herein, a series of K, B co-doped CN with various doping contents (K, B-CN-X) were developed by simple one-step calcination of melamine and KBH4. B was confirmed to replace the C site and K-N bond was formed, which was verified by XPS (X-ray photoelectron spectroscopy) and DFT (density functional theory) calculation. Particularly, K, B-CN-4 displayed the optimal catalytic performance in the presence of Bu4NBr (tetrabutylammonium bromide) cocatalyst for the CO2 cycloaddition with propylene oxide. Besides, K, B-CN-4/Bu4NBr catalyst exhibited good substrate versatility to various epoxides and excellent recycling performance. According to the DFT calculation on CO2 adsorption and experimental results, K, B-CN-4 presented satisfactory catalytic activity due to the enhanced CO2 adsorption after K and B dopings then the possible reaction mechanism was proposed. The promising K, B-CN-X catalyst presented an attractive application due to the simple, eco-friendly synthesis route for the efficient fixation of CO2. (C) 2021 Elsevier Inc. All rights reserved.

Automated summary

Efficient heterogeneous catalysts for the conversion of carbon dioxide (CO2) to high-value chemicals have been extensively studied. In this study, K, B co-doped CN catalysts were synthesized and showed optimal catalytic performance for the cycloaddition of CO2 to epoxides. The catalyst also exhibited good substrate versatility and recycling performance. The enhanced CO2 adsorption after K and B dopings contributed to the satisfactory catalytic activity.