Mechanistic study of partial oxidation of methane to synthesis gas over modified Ru/TiO2 catalyst

The mechanism of the partial oxidation of methane to synthesis gas over the Ru/TiO2(Ca2+) catalyst is investigated employing non-steady-state and stea dy-state isotopic transient experiments, combined with in situ DRIFT spectr oscopy. The main objective is to identify the active intermediate species i nvolved in surface transformations and the mechanistic reaction pathways. I t was found that gas-phase CH4 interacts with the catalyst surface, produci ng CH., surface species. This process is irreversible and is characterized by a slow rate. CHx species are fully dehydrogenated toward surface carbon. Adjacent metallic Ru sites as well as atomically adsorbed oxygen participa te in the process of hydrogen abstraction from CHx, species. The primary pr oduct of the reaction is CO, which results from the surface reaction betwee n carbon and adsorbed atomic oxygen on metallic Ru sites, while CO2 derives from CO oxidation on oxidized sites. The unique ability of the Ru/TiO2 cat alyst to promote the direct formation of H-2 and CO is attributed to its hi gh resistance to oxidation under conditions of partial oxidation of methane . (C) 2001 Academic Press.