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

Structure-function relationships of supported metal nanoparticle catalysts in the CO-assisted oxidation of ethane to ethanol were investigated. A rutile TiO₂-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 Pt⁰ 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 H₂O₂, which is the true oxidant for the reaction. The supported Pt nanoparticle uses in situ-generated H₂O₂ to activate ethane, where the C₂H₅OOH intermediate is formed through a nonradical mechanism and subsequently converted to C₂H₅OH. 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 low-temperature oxidation of ethane to ethanol.