An insight into the superior performance of a gold nanocatalyst on single wall carbon nanotubes to that on titanium dioxide and amorphous carbon for the green aerobic oxidation of aromatic alcohols

Gold nanocomposites based on three supports, single wall carbon nanotubes, carbon black and TiO2, were prepared using an in-situ reduction technique and characterized. They were tested for their suitability as heterogeneous catalysts in the green aerobic oxidation of 1-phenylethanol, 2-phenylethanol and benzylalcohol of industrial importance. For all reactions, the use of single wall carbon nanotubes as supports resulted in superior reaction efficiency and specificity for aldehyde to that of TiO2 and carbon black. The gold nanocatalysts can be reused over several reaction cycles with a minimal degeneration in catalytic activity. The activity of the gold nanoparticle catalyst was related to the shape and size of the gold particles and the properties of the support. The selectivity was ascribed to the functional groups on the substrate, the properties of the supports and the particle size distributions of the gold nanoparticles.