Nitrilethermal synthesis of CeO2-based composite nanoparticles as Ru and Pd catalyst supports for CO2 methanation and CH4 oxidation

Abstract

A one-pot and one-step solvothermal reaction in acetonitrile, termed ‘nitrilethermal’ synthesis, was developed to obtain CeO2 and CeO2-based composite nanoparticle assemblies, such as Al2O3−ZrO2, SiO2−CeO2, Y2O3−CeO2, and ZrO2−CeO2. The composites were prepared by heating a precursor solution containing Ce(NO3)3 with Al(NO3)3, Si(OEt)4, Y(NO3)3, or ZrO(NO3)2 as an oxide source and triethylene glycol as an additive in acetonitrile (or a mixed acetonitrile/ethanol solvent) at 300 °C for 10 min. Homogeneously mixed composite oxides with specific surface areas of 101−152 m2/g were obtained in all cases. The composites showed high oxygen storage capacities, with that of SiO2−CeO2 being especially high at >500 μmol-O/g. The impregnation method was used to apply the composites as supports for nanometal Ru and Pd catalysts for CO2 methanation and CH4 oxidation, respectively. Ru/SiO2−CeO2 demonstrated the slightly higher activity for CO2 methanation, while Pd/SiO2−CeO2 and Pd/Al2O3−CeO2 demonstrated superior low-temperature activities for CH4 oxidation.