On the deactivation of supported platinum catalysts for selective oxidation of alcohols

The oxidation of a variety of terminal alcohols with O2 in liquid water at 343 K over Pt supported on C, BN, SiO2, TiO2, and Al2O3 was explored to determine the origin of catalyst deactivation. The sintering of Pt nanoparticles and dissolution of Pt did not contribute significantly to the observed deactivation. A decrease in TOF for 1,6-hexanediol oxidation after the exposure of Pt/C to dioxygen was easily reversed by reduction with the alcohol substrate, indicating that over-oxidation of Pt was not the mode of deactivation. Strongly adsorbed CO on Pt was observed by ATR-IR spectroscopy after contacting the catalysts with alcohols, but the CO was easily removed by oxidation with dissolved O2. Results from thermogravimetric analysis and regeneration studies indicate a strongly adsorbed species other than CO and product acid deactivated the catalysts.