Novel approach to rhenium oxide catalysts for selective oxidation of methanol to DMM

New rhenium and rhenium–tantalum catalysts are prepared using alkoxide molecular precursors. The presence of the chemically bound oxidative (perrhenate) and acidic (tantalum oxide) components in the catalyst facilitates one-step production of DMM. [Display omitted] ► The Re and Re Ta alkoxides as catalyst precursors. ► Ambient atmosphere and low temperature for catalyst preparation. ► Catalytic conversion of methanol. ► One-step production of DMM. Novel rhenium oxide catalysts have been prepared by impregnation of mesoporous TiO 2-anatase support using amounts of homometallic, such as Re 4O 4(OEt) 12, and heterometallic, such as Ta 4O 2(OEt) 14(ReO 4) 2, rhenium alkoxide solutions with subsequent thermal treatment. The structure of the produced catalytic centers was investigated by X-ray diffraction, XPS, and IR spectroscopy in order to examine the role of Re in enhancing catalytic activity. It has been demonstrated that rhenium is mostly present as perrhenate ligands attached via an oxo-bridge to an oxide surface. The catalytic activity was studied for the selective oxidation of methanol as model reaction, revealing selectivity strongly dependent on the nature of the molecular precursor: in case of ReO x /TiO 2, the catalysts are showing selectivity to formaldehyde, and in case of ReO x /Ta 2O 5/TiO 2 to DMM in rich conditions.