Nitrogen-Doped, Metal-Free Activated Carbon Catalysts for Aerobic Oxidation of Alcohols

Various nitrogen-doped carbon materials were prepared via treatments of an activated carbon (AC) with ammonia and hydrogen peroxide, and their catalytic performance was tested for aerobic oxidation of several alcohols in ethanol. The amount and nature of doped nitrogen-species were examined by X-ray photoelectron spectroscopy to discuss the genesis of active species by nitrogen doping. The nitrogen-doped AC catalysts are active for the oxidation of such alcohols as benzyl alcohol, cinnamyl alcohol, and 5-(hydroxymethyl)-2-furaldehyde, and in some cases, they are even more selective to the oxidation of the hydroxyl group compared with conventional Pt/C and Ru/C catalysts, for which coupling products with the ethanol solvent are formed at low conversion levels. Graphite-type doped nitrogen species are significant for the formation of active sites on the surface of AC. The present results demonstrate the potential of nitrogen-doped AC materials as metal-free, carbon-based catalysts useable for organic synthetic reactions.