Direct synthesis of diethyl carbonate from CO ₂ and ethanol over flower‐like CeO ₂ catalyst with in situ water removal

BACKGROUND Diethyl carbonate (DEC) is a valuable linear organic carbonate widely used as a fuel additive, lithium‐ion battery electrolyte component, and intermediate for polycarbonate production. Direct synthesis of DEC from CO 2 and ethanol represents a sustainable route for CO 2 utilization; however, the reaction is thermodynamically limited due to water formation. Therefore, the development of efficient catalysts with suitable properties is essential to enhance catalytic performance. In this work, CeO 2 catalysts with distinct morphologies, namely flower‐like CeO 2 and CeO 2 nanoparticles, were synthesized and systematically evaluated for DEC synthesis. RESULTS The flower‐like CeO 2 exhibited significantly enhanced catalytic performance, achieving a DEC yield of 13.25 mmol DEC g cat −1 h −1 at 140 °C and 30 bar in the presence of 2‐cyanopyridine as a dehydrating agent. Comprehensive characterizations revealed that the superior activity of the flower‐like CeO 2 arises from its hierarchical porous architecture, higher specific surface area, and optimized surface acid–base properties. CO 2 and NH 3 temperature‐programmed desorption analyses demonstrated that DEC synthesis is governed by a cooperative acid–base mechanism and that an optimized acidity/basicity ratio is critical for the simultaneous activation of CO 2 and ethanol. Despite a slightly lower total basic site density, the flower‐like CeO 2 provided a more favorable distribution of weak‐to‐moderate acid and base sites, leading to improved site utilization and higher catalytic efficiency compared with CeO 2 nanoparticles. Furthermore, the catalyst demonstrates excellent structural and morphological stability after the reaction. CONCLUSION These findings highlight the critical role of catalyst morphology and acid–base balance in enhancing DEC synthesis and provide insights for the design of efficient catalysts for sustainable CO 2 conversion.