Synergistic Modulation of Surface Acid-Base Sites in Ti-Doped CuO Catalysts for Efficient Glycerol Carbonylation with CO2

The direct carbonylation of glycerol with CO2 to produce glycerol carbonate (GC) offers a promising approach to CO2 utilization and glycerol valorization, with high theoretical atom economy and H2O as the sole coproduct of the stoichiometric carbonylation reaction. However, this reaction is severely constrained by thermodynamic limitations and the kinetic inertness of CO2. In this work, we demonstrate that doping CuO with Ti cations creates an effective catalyst that addresses both challenges simultaneously. A combination of characterizations confirms the successful incorporation of Ti cations into the CuO lattice, generating Cu-O-Ti interfacial sites with improved surface acid-base properties. The optimized catalyst with a Ti/Cu molar ratio of 3% (3Ti-CuO) exhibits the highest density of acid and base sites. Under the optimized reaction conditions (0.5 g of catalyst, 150 °C, an initial CO2 pressure of 3.5 MPa, and 5 h), 3Ti-CuO achieved a superior GC yield of 51.9% with 89.2% selectivity. Moreover, the 3Ti-CuO catalyst demonstrates good stability with activity loss of less than 10% after several reaction cycles. The enhanced catalytic performance is attributed to the synergistic effect of the modified acid-base sites, where the basic sites facilitate CO2 activation and the acidic sites promote the hydration of 2-cyanopyridine to remove H2O, thereby shifting the reaction equilibrium and enabling high GC productivity.