CO2 to dimethylcarbonate synthesis: surface defects and oxygen vacancies engineering on MOF-derived CexZr1-xO2-y catalysts

Abstract

Direct reaction of carbon dioxide and methanol to produce dimethylcarbonate (DMC) is an interesting process that allows the synthesis of such valuable product in a more environmentally friendly route than the present technology that is expensive, unsafe and use toxic raw materials. Unfortunately, this alternative presents intrinsic limitations as the low yield due to thermodynamic limitation and reaction mechanism remains unclear. Herein, we propose a reproducible synthetic methodology of cerium oxide and Ce/Zr oxide solid solutions by calcination of opportune UiO-66(Ce/Zr) MOFs, employed as sacrificial precursors. The higher defectivity of these nanomaterials, corroborated by IR of adsorbed CO, in comparison with commercially-available ones, as those synthesized by traditional sol-gel methods, plays a pivotal role in the direct synthesis of DMC. Lastly, reaction mechanism was systematically and in-depth investigated by in situ AP-NEXAFS and MCR-ALS/LCF augmented IR spectroscopy, unveiling the role of oxygen vacancies towards CH₃OH activation.