Reductive Amination of Ketones with Benzylamine Over Gold Supported on Different Oxides

Reductive amination of cyclohexanone with benzylamine was investigated at 100 °C under 30 bar hydrogen in toluene with five different gold catalysts prepared by deposition–precipitation method and supported on TiO2, La2O3/TiO2, CeO2/TiO2, La2O3 and CeO2. Size of metallic gold varied in the range of 2.6–3.6 nm. The best catalysts in reductive amination of cyclohexanone with benzylamine were 4 wt% Au/TiO2 and 4 wt% Au/CeO2/TiO2 giving 72% and 79% yield of the desired amine. The most acidic and basic catalysts were also unselective and exhibited low activity towards imine hydrogenation. The best catalyst 4 wt% Au/CeO2/TiO2 gave in reductive amination of propiophenone 56% selectivity to the corresponding amine at 20% conversion in 5 h.