FTIR studies on the selective oxidation and combustion of light hydrocarbons at metal oxide surfaces .2. Propane and propene oxidation on Co3O4

The interaction of propane and propene and of C-3, C-2 and C-1 oxygenates (propan-1-ol, propan-2-ol, allyl alcohol, acetone, propanal, acrolein, acrylic, propionoic, acetic and formic acids and CO2) on oxidized Co3O4+x has been studied by FTIR spectroscopy, with the aim to collect data on the mechanism of hydrocarbon catalytic combustion. Propene is already oxidized to acrylate species at RT and burns completely starting from 473 K. Propane already gives rise to acetate, propanoate and acrylate species below 373 K. A reaction scheme for catalytic propane oxidation is proposed. The behaviour of Co3O4+x combustion catalyst surfaces are compared with those of MgCr2O4+x, previously investigated. In both cases nucleophilic oxygen species (lattice O2- anions at the oxidized surface) are thought to be involved in catalytic combustion, which occurs via overoxidation of adsorbed partially oxidized compounds.