Partial oxidation of methane on potassium-promoted WO3/SiO2 and on K2WO4/SiO2 catalysts Original Research Article

The partial oxidation of methane to formaldehyde or ethane and ethylene was studied on K2WO4 deposited on various supports, on potassium-promoted WO3/SiO2 and for comparison on WO3/SiO2 in a fixed-bed continuous-flow reactor at 860–923 K using O2 as oxidant. The catalysts were characterised by Raman, XP spectroscopy and TPR method. It was found that the original structure of potassium tungstate remained on K2WO4/SiO2, whereas K2W2O7 was very likely formed on K+WO3/SiO2. The main products of the reaction besides the carbon oxides were HCHO on WO3/SiO2 while on K-containing samples mainly the C2 hydrocarbons were formed. The product distribution of the oxidation reaction was markedly influenced by the nature of the support. The highest activity was measured for alumina-supported catalyst. In this case, however, only traces of partially oxidised products were formed. Formaldehyde, in a larger quantity, was produced on WO3/SiO2 but C2 in higher selectivity on K2WO4/SiO2 was formed. A possible mechanism for the oxidative conversion of methane is also discussed.