Synthesis and characterization of ceria-supported catalysts for carbon dioxide transformation to diethyl carbonate
The support materials Al₂O₃, SiO₂ and TiO₂ were modified with 16 wt% CeO₂, using two different preparation methods evaporation-impregnation and precipitation-deposition. The synthesized 16 wt% CeO₂-Al₂O₃, 16 wt% CeO₂-SiO₂ and 16 wt% CeO₂-TiO₂ materials were characterized by means of X-ray powder diffraction for the phase purity, scanning electron microscopy for the morphology, nitrogen physisorption to determine the specific surface area and X-ray photo electron spectroscopy for the oxidation state of the Ce in the TiO₂, Al₂O₃ and SiO₂ matrices. Transmission electron microscopy was used to study the particle size of CeO₂ whereas CO₂-temperature programmed desorption (TPD) was used to determine the basicity of ceria-modified TiO₂, Al₂O₃ and SiO₂ catalysts. Furthermore, the catalytic performance of the as prepared CeO₂-modified catalysts were compared in the synthesis of diethyl carbonate starting from ethanol and CO₂ using butylene oxide as the dehydrating agent. The physico-chemical characterization results were correlated with the catalytic activity results and discussed in detail.