Spectroscopy and catalytic activity study of gold supported on barium titanate nanotubes for styrene epoxidation

• Au/BaTNT catalyzes epoxidation of styrene with molecular oxygen/peroxides.
• Oxidation of styrene enhances when H2 was co-dosed with O2.
• The Au catalysts activate O2/H2 producing H2O2in situ for further use in oxidation.
• These catalysts are reusable and oxidation occurs even at ambient conditions.
• DRUV-vis and FT-Raman provided evidence for formation of reactive oxygen species.

Gold (0.5–5 wt.%) supported on barium titanate nanotubes (Au/BaTNT) were prepared, characterized and for the first time, investigated as catalysts for selective oxidation of styrene with oxygen (O2 or H2 + O2) and peroxides (H2O2 or TBHP). Conversion of styrene enhanced when H2 was co-added to O2 in the reactions. Au/BaTNT activated O2 and H2 and produced H2O2in situ for use in oxidations. Peroxides were found better oxidants than O2. At optimized conditions, styrene oxide selectivity of 80.1 wt.% at styrene conversion of 60.5 wt.% was achieved over Au(1 wt.%)/BaTNT using TBHP. Au particles (5.0–7.4 nm) were dispersed and decorated on the walls of BaTNT. They exhibited superior performance to the known Au catalysts in styrene oxidation. Reactive oxygen species formed during oxidation reactions were followed with in situ spectral characterizations (diffuse reflectance UV–vis and FT-Raman). Au/BaTNT was reusable in four recycles with little loss in catalytic activity.

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