Photocatalytic oxidation of methane to methanol over zinc titanate supported silver catalysts

The direct activation of methane under mild condition to achieve highly selective of oxygenates is a challenging project. In this study, a well dispersed silver supported ZnTiO3 catalyst was prepared to achieve selective preparation of methanol from methane and water under mild condition. X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) characterizations demonstrate that Ag species are uniformly dispersed on ZnTiO3 surface in the form of metallic silver nanoparticles. The photoelectric characterizations reveal that the addition of silver species enhances light absorption and promotes charge separation of the catalysts. Under the reaction conditions of 50 °C and 3 MPa, the methanol is obtained as the only liquid product over the designed Ag/ZnTiO3 catalyst under light irradiation. In this photocatalytic process, the holes generated by ZnTiO3 activate water to produce intermediate ·OH, which further reacts with methane to synthesize methanol. The silver species as co-catalyst extend the light absorption range of ZnTiO3 as well as promote charge separation.