Influence of Co₂ on the Catalytic Performance Of La₂O₃/CeO₂ and CaO/CeO₂ Catalysts in the Oxidative Coupling of Methane

In this work the La₂O₃/CeO₂ (33 mol % of La) and CaO/CeO₂ (33 mol % of Ca) catalysts were prepared by the impregnation method and characterized by XRD and CO₂-TPD. The catalytic properties of the catalysts were tested in the OCM process at 1073 K using the methane/oxygen mixture of the mole ratio 3.7 or 2.5 additionally containing CO₂ and helium balance. It was found that in the presence of both catalysts an addition of CO₂ enhances the selectivity to the ethylene and ethane and it does not have any negative influence on methane conversion. In the case of the CaO/CeO₂ catalyst the promoting effect of CO₂ was the highest. When the partial pressure of CO₂ equals to 39 kPa the increase in selectivity from 36 to 41% was noted while the conversion of methane equal to 19.4-19.7 %.