Novel Perovskites Containing Ba, Mg, Ca, Nb, Fe and Ta for Electrochemical Oxidative Coupling of Methane

Abstract

Methane is the major component of many gas sources such as natural gas and shale gas and more than 500 million tons of methane is produced every year. Unfortunately, most of it is burnt as an energy source due to difficulties in converting it into easily transportable fuels. Oxidative and non-oxidative coupling of methane (OCM and NOCM) has been actively researched to produce ethylene and higher olefins from methane although catalysts with commercially viable conversion rates have not been developed yet.[1] Electrochemical OCM (EC-OCM) is gaining attention due to its ability to regulate the oxide ion flux that will help reduce the over-oxidation of methane while also helping to activate methane.[2] Fe based catalysts have been shown to activate methane in both OCM and NOCM although suffer from coking related durability challenges. We have developed two novel perovskites comprising Ba, Ca, Mg, Nb and Ta where incorporation of Fe in the crystal lattice has resulted in mixed ionic electronic conductivity. Their physical and chemical properties are evaluated using TGA, XRD, XPS and FT-IR measurements. We further examined these catalysts for EC-OCM along with structural and chemical stability characterizations. Both these perovskites show very good chemical stability in methane under EC-OCM conditions. TGA under methane environment further reveal adsorption of methane on our perovskite material at about 600°C. Ethylene production was observed to increase with increasing Fe content in the perovskite structure. In this presentation we report our findings on the application of both perovskites towards EC-OCM and discuss potential future directions. References Schwach, X. Pan, and X. Bao, “Direct Conversion of Methane to Value-Added Chemicals over Heterogeneous Catalysts: Challenges and Prospects,” Chem. Rev., 117, 8497, 2017. Zhu, S. Hou, X. Hu, J. Lu, F. Chen, and K. Xie, “Electrochemical conversion of methane to ethylene in a solid oxide electrolyzer,” Nat. Commun., 10, 1173, 2019.