Reaction mechanism of propane oxidation over Co3O4 nanorods as rivals of platinum catalysts.

• Co 3 O 4 nanorods are active for catalytic oxidation of propane. • The extraction of hydrogen from C-H bonds is kinetically relevant. • Propane oxidation takes place via the Langmuir-Hinshelwood model on Co 3 O 4. • Propane oxidation takes place via the Eley-Rideal model on platinum catalysts. Co 3 O 4 nanorods and Pt/Al 2 O 3 catalysts were synthesized and tested for catalytic oxidation of propane. In comparison to Pt/Al 2 O 3 , the catalytic results showed that Co 3 O 4 nanorods were more active for propane oxidation under relatively high space velocity. Kinetic data suggested that the extraction of hydrogen from C-H bonds in propane can be considered as the reaction of kinetic relevance for both Co 3 O 4 nanorods and Pt/Al 2 O 3 catalysts. On both catalysts, propane could be first transformed into C 3 H 7 O* species. The intermediates further dissociate and are oxidized into carboxylates, with acetate and/or formate species as the primary products detectable by Fourier-transform infrared spectroscopy (FTIR). These species are later oxidized into CO 2 and H 2 O as final products. However, the specific oxidation pathways might be different over these two catalysts. Over Co 3 O 4 nanorods, propane oxidation appears to take place via the Langmuir-Hinshelwood mechanism. The rate-determining step is the C–H bond activation by the abstraction of H from adsorbed propane on two neighboring oxygen atoms. In contrast, on Pt/Al 2 O 3 catalysts, the propane oxidation reaction follows an Eley-Rideal mechanism, and the rate-determining step is the activation of gaseous C 3 H 8 on a neighboring oxygen atom and a vacant site. [ABSTRACT FROM AUTHOR]