Highly selective oxidation of benzyl alcohol to benzaldehyde catalyzed by nano Au/ gamma -Al sub(2)O sub(3) under environment-friendly conditions

The liquid phase oxidation of benzyl alcohol to benzaldehyde under environment-friendly conditions has been investigated. Water is used as a medium to replace toxic organic solvents. The reaction used hydrogen peroxide as the oxidant. The novel green reaction was catalyzed by nano Au/ gamma -Al sub(2)O sub(3). Gold nanoparticles supported on gamma alumina ( gamma -Al sub(2)O sub(3)) were prepared by a deposition-precipitation method. These synthesized materials were characterized by several techniques such as X-ray diffraction, N sub(2) low temperature adsorption, and transmission electron microscopy. The benzaldehyde selectivity changed depending on the supports, the Au loading and the reaction temperature. Over 98 % selectivity of benzaldehyde was observed at 60 degree C after 2 h on the 2 % Au supported on gamma -Al sub(2)O sub(3) which was calcined at 550 degree C.