OXYGEN PATHWAYS IN METHANE SELECTIVE OXIDATION OVER SILICA-SUPPORTED MOLYBDENA

Oxygen pathways for CH4 partial oxidation over a silica-supported molybdena catalyst were investigated using a series of oxygen isotopic exchange experiments and steady state oxygen isotope transients. The initial source of oxygen in the products is masked by rapid and extensive oxygen exchange between the catalyst and the products CO2 and HCHO. This exchange process occurs at the surface molybdena site and is accompanied by rapid O interchange between the surface and support phases which allows access to the bulk of the support. Laser desorption Fourier transform mass spectra, LDFTMS, indicate equal enrichment of O-18 in both the silica and molybdena fragments.