Preparation and characterization of Mg-modified zirconias as catalysts for the direct synthesis of dimethyl carbonate (DMC)

In this work sol-gel zirconia was prepared using H2SO4, HNO3 or HCl as hydrolysis catalysts. Basic and acid sites of synthesized zirconia materials were characterized by XRD, BET, FTIR, CO2-TPD and NH3-TPD. FTIR spectra and TGA confirmed the presence of sulfate in the structure of samples prepared with H2SO4 as hydrolysis catalyst. Different molar ratios of Mg were incorporated by co-gellation on selected zirconia materials in order to improve their basic properties. Mg loading was determined by elemental analysis. The resulting materials were tested for the direct synthesis of dimethyl carbonate (DMC) from methanol and CO2. The addition of Mg to zirconia samples prepared with HCl as hydrolysis catalyst increased their CO2 adsorption capacity between 100 and 200 degrees C. However, methanol conversions on these samples were lower than over unmodified zirconia samples.