Ceria-Based Catalysts for the Direct Conversion of CO2 to Dimethylcarbonate

This master’s thesis focuses on exploring the catalytic properties of cerium oxides synthesized using different methods for the conversion of CO2 and methanol into dimethyl carbonate (DMC). The three types of cerium oxides studied in this work were: CeO2 MOF, prepared by direct calcination of the metal-organic framework UiO-66 to maintain high surface defectivity; CeO2 SCS, produced via solution combustion synthesis, and CeO2 HSA, developed in collaboration with the University of Udine to achieve a high surface area. To characterize these materials, a variety of techniques was employed. Powder X-ray Diffraction (PXRD) with Rietveld refinement was used to confirm phase purity and determine lattice parameters. BET analysis assessed the specific surface areas through nitrogen physisorption at low temperatures. CO adsorption monitored by FT-IR spectroscopy helped in identifying the presence of coordinatively unsaturated sites. Additionally, Near Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy was used to investigate the oxidation state of cerium during CO2 and methanol adsorption at elevated temperatures. Finally, FT-IR spectroscopy provided detailed insights into the interactions of CO2 and methanol with the catalysts at both room and elevated temperatures. The catalytic efficiency of the cerium oxides was evaluated by measuring the DMC yield from the reaction of CO2 with methanol. The purpose of this project was to understand how different synthesis methods impact the catalytic behavior of cerium oxides and to identify the most effective catalyst for DMC production. This research aims to contribute to the development of efficient catalysts for CO2 conversion, addressing the environmental challenges posed by CO2 emissions.