Selective deactivation of gold catalyst

The progressive poisoning effect of different molecules on carbon supported gold catalysts has been evaluated during the aerobic oxidation of glucose. A geometrical model has been derived for describing the morphological properties of two catalysts made of carbon supported gold particles having a known size distribution centered at 3.30 and 7.89 nm respectively. The observed deactivation trend follows the order thiocyanate > cyanide ≈ cysteine > thiourea and it obeys an exponential law. The kinetics of catalyst deactivation has been interpreted by considering the important contribute of electronic factors which overlap the space shielding of active sites, due to long range poison-catalyst interaction influencing the entire metal particle. Considering the nature of the molecules showing a high poisoning effect and the promoting effect of OH-, a molecular model for electronic interactions in gold nanoparticles during the aerobic oxidation of glucose has been proposed where the dioxygen reduction step is differently influenced by soft and hard-nucleophiles.