Gold sols as catalyst in the glycerol oxidation: the role of stabilizer

Polyvinylalcohol (PVA), tetrakis hydroxypropyl phosphonium chloride (THPC) and citrate-stabilized gold nanoparticles (AuNPs) have been synthesized and tested in the liquid phase oxidation of glycerol. THPC stabilized gold NPs have been found to exhibit remarkable catalytic activity (TOF 2478 h-1) in comparison to PVA and citrate ones (TOF respectively of 715 and 160 h-1). The catalytic results can be explained in terms of particle size but aging treatment revealed also the influence of the protective agent. PVA as stabilizer produced small and quite stable gold nanoparticles differently from the THPC system. However PVA also limits the accessibility of reactant to the active sitemight be of interest for some carbohydrate conversion reactions where strong basic sites are required but for which the pH of the solution should remain mild in order to avoid the degradation of the reactants and/or product