Mechanochemically Engineered CaO–CeO₂ Dual-Function Catalysts for Sustainable Glycerol Carbonate Production without Solvents

Upgrading biorefinery-derived waste such as glycerol to fuel-additives and high-value products is essential to further enhance the productivity, profitability, and circularity of the biorefinery concept to achieve a green and sustainable net-zero world. This study explores the catalytic conversion of glycerol into glycerol carbonate using calcium oxide-cerium oxide (CaO-CeO₂) dual-function catalytic materials. Herein, a clean and efficient approach was developed to synthesize CaO-CeO₂ materials using a green mechanochemical method and then utilize these as catalyst in sustainable and solvent-free synthesis of glycerol carbonate to enhance the circular economy of biorefineries while reducing their carbon footprint. The catalysts were comprehensively characterized using XRD, FTIR, ICP, N₂ sorption, CO₂-TPD, and SEM/EDS analyses and evaluated for their catalytic activity. Among the catalysts studied, 40 wt % CaO-CeO₂ exhibited the highest catalytic activity, achieving 95% glycerol conversion and 99% selectivity to glycerol carbonate under optimized conditions (10 wt % catalyst loading relative to glycerol, 90 °C, 60 min, and a glycerol/ DMC molar ratio of 1:3). This catalyst showed excellent reusability, maintaining high conversion over four cycles. The transesterification reaction followed irreversible second-order reaction kinetics with an activation energy of 46.9 kJ mol^-1. The synergistic interplay between the basic sites of the Ca²⁺-O^2- pair and the oxygen vacancies in the CeO₂ matrix at the CaO-CeO₂ interface work in tandem to enhance the catalytic activity for glycerol carbonate production. We have developed a highly efficient, cost-effective, and environment-friendly approach for the sustainable production of glycerol carbonate from glycerol.