Rutile TiO₂-Supported Pt Nanoparticle Catalysts for the Low-Temperature Oxidation of Ethane to Ethanol

Abstract

Structure−function relationships of supported metal nanoparticle catalysts in the CO-assisted oxidation of ethane to ethanol were investigated. A rutile TiO 2 -supported Pt nanoparticle catalyst exhibited the highest ethanol production rate and selectivity. During the reaction, sequential changes in the geometric/electronic states and the particle size of the Pt nanoparticles were observed. The comparison of the catalytic performances of model catalysts with controlled metal−support interactions revealed that Pt 0 nanoparticles of 2−3 nm with a high fraction of the surface Pt δ+ species are highly active for the oxidation of ethane to ethanol. The coadded CO plays a pivotal role not only in tuning the oxidation state of the surface Pt but also in producing H 2 O 2 , which is the true oxidant for the reaction. The supported Pt nanoparticle uses in situ-generated H 2 O 2 to activate ethane, where the C 2 H 5 OOH intermediate is formed through a nonradical mechanism and subsequently converted to C 2 H 5 OH. This reaction occurs even at 50 °C with an apparent activation energy of 32 kJ mol −1 . The present study sheds light on the usefulness of surface-engineered Pt nanoparticles for the lowtemperature oxidation of ethane to ethanol.