Experimental study on the influence of alkaline earth promoters on neodymium oxide performance in the oxidative coupling of methane

The catalytic performance of Nd2O3 promoted with different alkaline earth oxides, i.e., MgO, CaO, SrO, and BaO was studied in the reaction of oxidative coupling of methane. The catalytic activity and selectivity were discussed mainly in relation to different basicity and the ability of the added altervalent cations to incorporate into the host Nd2O3 lattice. To elucidate the complex relationships between composition, basicity, electrical conductivity, and catalyst performance, the catalyst samples were characterized by XRD, TPD of CO2 and electrical conductivity measurements. The highest selectivity towards C2+ hydrocarbons was observed on Sr promoted catalyst. Such behavior is probably due to the presence of stronger basic centers and Sr good incorporation into Nd2O3 lattice, thanks to the close cation radii of Nd3+ and Sr2+.