Promotion by strontium fluoride of neodymium oxide catalysis of the oxidative coupling of methane

Abstract

Catalytic performance measurements showed that CH4 conversion and C2 selectivity were higher over SrF2/Nd2O3 catalyst than over pure Nd2O3 for the oxidative coupling of methane (OCM). XRD indicated that there was some exchange of F− and O2−, leading to the formation of tetragonal and rhombohedral NdOF phases during the catalyst preparation. After a certain amount of SrF2 was added to Nd2O3, the increase in surface basicity and conductivity, as well as the role of F− on the dispersion of surface active sites, would be favourable to a decrease in the secondary deep oxidation of methyl radicals and C2 hydrocarbons, giving improved C2 selectivity. Since there is a certain correlation between methane conversion and C2 selectivity for an oxygen-limited OCM reaction, methane conversion is also expected to increase with the increase in C2 selectivity.