Enhancing DMC Production from CO 2 : Tuning Oxygen Vacancies and In Situ Water Removal

The direct synthesis of dimethyl carbonate (DMC) from methanol and CO 2 presents an attractive route to turn abundant CO 2 into value-added chemicals. However, insufficient DMC yields arise due to the inert nature of CO 2 and the limitations of reaction equilibrium. Oxygen vacancies are known to facilitate CO 2 activation and improve catalytic performance. In this work, we have demonstrated that tuning oxygen vacancies in catalysts and implementing in situ water removal can enable highly efficient DMC production from CO 2 . Ce x Zr y O 2 nanorods with abundant oxygen vacancies were synthesized via a hydrothermal method. In liquid-phase DMC synthesis, the Ce 10 Zr 1 O 2 nanorods exhibited a 1.7- and 1.4-times higher DMC yield compared to CeO 2 nanoparticles and undoped CeO 2 nanorods, respectively. Zr doping yielded a CeZr solid solution with increased oxygen vacancies, promoting CO 2 adsorption and activation. In addition, adding 2-cyanopyridine as an organic dehydrating agent achieved an outstanding 87% methanol conversion and >99% DMC selectivity by shifting the reaction equilibrium to the desired product. Moreover, mixing CeO 2 nanoparticles with hydrophobic fumed SiO 2 in gas-phase DMC synthesis led to a doubling of DMC yield. This significant increase was attributed to the faster diffusion of water molecules away from the catalyst surface, facilitated by the hydrophobic SiO 2 . This study illustrates an effective dual strategy of enhancing oxygen vacancies and implementing in situ water removal to boost DMC production from CO 2 . The strategy can also be applied to other reactions impacted by water accumulation.