Modification of active catalytic sites with N2O and CO2 as gas promoters during oxidation reactions

The influence of adding 300 ppm of N2O in the feed during the oxidative dehydrogenation of propane and 3% of CO2 during the oxidation of methane was studied using a mixture of NiMoO4 and α-Sb2O4, and a palladium supported on a mixed Zr-Ce-O oxide catalyst, respectively. In both cases, the selective sites are modified by the presence of the gas dopes. With N2O, the selectivity to propylene increases, while the conversion of both propane and oxygen and the yield in CO2 decreases. N2O promotes the reduction of molybdenum. CO2 promotes total oxidation of methane. The dissociation of CO2 seems to be responsible for this promotion. The adjustment of the concentration of N2O and CO2 thus clearly appears as a promising tool to improve the selectivity of partial oxidation products and the energetic efficiency in combustion.