PARTIAL OXIDATION OF METHANE TO FORMALDEHYDE ON SILICA-SUPPORTED TRANSITION-METAL OXIDE CATALYSTS

This work describes the partial oxidation of methane on high surface a rea silica-supported redox oxide catalysts (MO(x)/SiO2; M = V, Mo, W a nd Re). Formaldehyde, C2Hn, and CO2 are primary products obtained in t his reaction, while CO originates from further oxidation of formaldehy de and hydrocarbons. Supported vanadium oxide was found to be the most reactive due to its higher reducibility, thus providing additional si tes for oxygen activation. Rhenium oxide exhibited high specific activ ity and selectivity, however it deactivates from sublimation of metal oxide under on-stream operation at high temperatures, typically above 773 K. Results suggest a reaction scheme where oxygenates and oxygen-f ree intermediates are present yielding HCHO, COx and C2Hn hydrocarbons .