(308e) Effects of Low Dopant Concentrations on the Performance of Samarium Oxide in the Oxidative Coupling of Methane

The oxidative coupling of methane (OCM) is a potential synthesis route to produce ethylene directly from methane, or natural gas, in one step. A number of different materials have been investigated in this reaction, but few catalysts display high activity, thermally stability and selectivity towards C₂₊ products (ethane, ethylene and higher hydrocarbons). Some of the most promising catalysts tend to be complex mixtures of oxides which makes identifying structure activity relationships challenging. To simplify the structure activity relationship in order to investigate fundamental effects, we have chosen to study the effects of low molar dopant concentrations on samarium oxide (Sm₂O₃) in the oxidative coupling on methane. We found that even at concentrations as low as 0.1 and 1.0 mol %, the dopants affect the methane conversion and the selectivity to ethane and ethylene of samaria with the highest increases in catalyst efficacy observed on 0.1% loading. Catalyst characterizations reveal that the dopants affect the crystal structure, as well as the number and strength of the basic sites, of samaria both of which are expected to influence the OCM properties.