CO-Assisted Methane Oxidation into Oxygenates over Surface Platinum-Titanium Alloyed Layers.

Methane oxidation using molecular oxygen remains a grand challenge in which the obstacle is not only the activation of methane but also the reaction with oxygen, considering the mismatch of the ground spin states. Herein, we report TiO 2 -supported Pt nanocrystals (Pt/TiO 2 ) with surface Pt-Ti alloyed layers that directly convert methane into oxygenates by using O 2 as the oxidant with the assistance of CO. The oxygenate yield reached 749.8 mmol g Pt -1 in a H 2 O aqueous solution over 0.1% Pt/TiO 2 under 31 bar of mixed gas (20:5:6 CH 4 :CO:O 2 ) at 150 °C for 3 h, while the CH 3 OH selectivity was 62.3%. On the basis of the control experiments and spectroscopic results, we identified the surface Pt-Ti alloy as the active sites. Moreover, CO promoted the dissociation of O 2 on the surface of Pt-Ti alloyed layers and the subsequent activation of CH 4 to form oxygenated products.