Oxidation of styrene to benzaldehyde and styrene oxide over nickel and copper ceria solution combustion catalysts

CeO2, Cu0.05Ce0.95O2-δ, Ni0.04Ce0.96O2-δ, Cu0.05Ni0.05Ce0.90O2-δ, catalysts were synthesised via solution combustion technique using urea as a fuel. The as pre-preared catalysts were characterised via X-ray powder diffraction, Brunauer-Emmett-Teller surface area analysis, transmission and scanning electron microscopy analysis. The characterisation techniques strongly suggested that all the catalysts were prepared successfully, and that copper and nickel were successfully incorporated into the lattice structure of ceria. The effect of the reaction conditions on the catalytic properties of the synthesised material were studied in detail using Cu0.05Ni0.05Ce0.90O2-δ as the model catalyst. The effect of temperature, solvents and co-oxidants was investigated in optimisation studies. A combination of acetonitrile, tert-butyl hydroperoxide and a temperature of 60 °C were found to be optimal after 24 hours and used for all catalysts. All catalysts were found to be active in styrene oxidation under these conditions, with styrene conversion as high as 69% over Ni0.04Ce0.96O2-δ, and selectivity to benzaldehyde and styrene oxide 38 and 26% respectively.