Selective Oxidation Of Methane On Antimony Oxide And Antimony-vanadium Mixed Oxide Catalysts

Methane selective oxidation to formaldehyde and methanol has been highly desirable but still remains extremely challengeable in catalysis. In this thesis, we investigated SbO_x/SiO₂ and SbVO/SiO₂ catalysts in the methane selective oxidation and the structure-performance relationship of SbO_x/SiO₂ and SbVO/SiO₂ catalysts by various characterization methods, including XRD and UV Raman spectroscopy. The main results are summarized as follows:In the methane selective oxidation over SbO_x/SiO₂ catalysts with O₂, 3.9% methane conversion with 11.5% formaldehyde selectivity can be obtained at 650°C. This result is similar to that for traditional molybdenum oxide catalysts. It was found that highly isolated and low oligomeric SbO_x species show higher activity than aggregated SbOx species. In the methane selective oxidation over Sb₂O₅/SiO₂ catalysts with O₂-NO, 17.3% methane conversion, 30.8% C|-oxygenates selectivity and 5.3% C₁-oxygenates yield can be obtained at 600°C. It was found that the formation of formaldehyde is favored on the surface of Sb₂O₅SiO₂ catalysts via a catalytic process but methanol is generated mainly in gas phase.In the methane selective oxidation over SbVO/SiO₂ catalysts with O₂, 20% methane conversion can be achieved with 15% formaldehyde selectivity at 650°C and thus a 3% formaldehyde yield can be obtained. This formaldehyde yield is much higher than that for Sb₂O₅SiO₂ catalysts and is more than two times than...