An Experimental Study of Glycerol Carbonate Synthesis over g-C3N4 Catalysts

This study examines a catalyst based on graphitic carbon nitride (g-C3N4) for synthesizing glycerol carbonate through the coupling reaction of glycerol and CO2. In this research, we focus on simultaneously improving CO2 emission reduction and glycerol valorization by co-doping g-C3N4 with phosphorus (P), sulfur (S), magnesium (Mg), and lithium (Li) for a better catalytic performance. The catalysts were prepared through a one-step thermal condensation process and characterized using XRD, SEM, TGA, FTIR, and nitrogen adsorption–desorption techniques. The co-doping further enhanced the surface chemical properties, Lewis acidity, basicity, and thermal stability, evidenced by the lower crystallinity, wider pore, and better catalytic performance as assessed through glycerol carbonylation reaction, optimized using a Box–Behnken design. The MgPSCN catalyst exhibited the highest glycerol conversion (68.72%) and glycerol carbonate yield (44.90%) at 250 °C, using 50 mg catalyst and 10 bar pressure. The model accuracy was validated by ANOVA (R2 > 0.99; p values < 0.0001). The results indicated that doping significantly enhanced the catalytic performance, most likely due to improved electron charge transfer and structural distortions within the g-C3N4 framework. Such a process highlights the potential of co-doped g-C3N4 catalysts for the sustainable glycerol utilization and valorization of CO2 through a scalable pathway toward green chemical synthesis—an approach that comes in line with worldwide decarbonization goals.