Selective oxidation of methane to methanol and methyl hydroperoxide over palladium modified MoO3 photocatalyst under ambient conditions

摘要

Selective partial oxidation of methane to valuable oxygenated products remains a great challenge, as typically over oxidation of oxygenated products to COx is observed. Weak oxidative species on the catalyst surface have a great potential to overcome this limitation. However, weak oxidative species usually have low concentrations and are easily decomposed. Here we report a Pd/MoO3 photocatalyst which can realize excellent methane oxidation to methanol and methyl hydroperoxide in pure water, under simulated solar light by in situ generated H2O2 at room temperature and pressure. The combined selectivity for methanol and methyl hydroperoxide is up to 98.6%, representing a productivity rate of 42.5 mu mol g(cat)(-1) h(-1). Further studies on the reaction mechanism indicate that PdO species on the Pd loaded MoO3 catalyst play an essential role in the suppression of over oxidation. In this case PdO traps the photo-generated electrons, leaving photo-generated holes for decomposition of H2O2 into weak oxidative hydroperoxyl radicals which are not involved in the formation of over oxidation products.