Supported gold nanoparticle catalysts for wet peroxide oxidation

Supported gold nanoparticles are of promising interest in wet hydrogen peroxide oxidation processes due to their efficient hydrogen peroxide consumption and adequate stability. Here, the origin of the catalytic properties of gold in this environmental process is explored by analyzing the influence of the support and the particle size on the activity of supported gold nanoparticles along with the influence of the nature of the target pollutant on the gold reactivity. The reaction mechanism for the oxidation of phenol with activated carbon-supported gold nanoparticles is proposed and the selectivity evaluated. A reaction pathway has been also proposed.The results demonstrate that wet peroxide oxidation is a support and gold size dependent reaction. Activated carbon is the preferable candidate versus TiO2 and Fe2O3 supports and small gold nanoparticles, desirably lower than 3 nm, show the highest TOF values. Supports showing adsorption capacity towards the target pollutant contribute to a more efficient use of hydrogen peroxide and, improve the TOF values for the oxidation and mineralization. Organic pollutants forming intermediate complexes with gold, viz. alcohols, are more efficiently oxidized. The inclusion of gold improves substantially the selectivity towards mineralization with respect to the bare activated carbon.

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► Wet peroxide oxidation is a gold size and support dependent reaction.
► Particle sizes ≤3 nm and supports with high adsorption capacity are beneficial for gold activity.
► Gold improves the selectivity towards mineralization.
► The process is more efficient for organic pollutants with affinity towards gold.
► The oxidation process occurs on the gold surface as well as in the liquid phase.