Selective Oxidation of Glycerol Catalyzed by Gold Supported on Multiwalled Carbon Nanotubes with Different Surface Chemistries

Carbon nanotubes with different levels of oxygenated groups on the surface were used as supports for gold nanoparticles and tested in glycerol oxidation. It was concluded that the support has an active role in the catalytic performance. Gold is highly active and selective when the support has only a limited amount of oxygenated groups on the surface. These groups, mainly those with acid character, are unfavorable for the catalytic activity, and their presence promotes the formation of overoxidation products, such as glycolic acid. Accordingly, turnover frequency values vary between 30 and 1870 h(-1) depending on the support used. Oxygen-free carbon nanotubes lead to selectivities toward glyceric acid as high as 60%, whereas only 40% was obtained with oxygen-rich supports.