Chemical Stability of BaMg_0.33Nb_0.67-XFe_xO_3-δ in High Temperature Methane Conversion Environments

Abstract

Doped perovskite metal oxide catalysts of the form A(BxM1-x)O3-δ have been instrumental in the development of solid oxide electrolyzers/fuel cells. In addition, this material class has also been demonstrated to be effective as a heterogeneous catalyst. Co-doped barium niobate perovskites have shown remarkable stability in highly acidic CO2 sensing measurements/environments (1). However, the reason for their chemical stability is not well understood. Doping with transition metal cations for B site cations often leads to exsolution under reducing conditions. Many perovskites used for the oxidative coupling of methane (OCM) or the electrochemical oxidative coupling of methane (E-OCM) either lack long term stability, or catalytic activity within these highly reducing methane environments. The Mg and Fe co-doped barium niobate BaMg0.33Nb0.67-xFexO3-δ shown activity in E-OCM reactors over long periods (2) (>100 hrs) with no iron metal exsolution observed by diffraction or STEM EDX measurements. In contrast, iron decorated BaMg0.33Nb0.67O3 showed little C2 conversion activity.

Electrochemical Oxidative Coupling of Methane: Deciphering the Exceptional Properties of BaMg0.33Nb0.67–xFexO3−δ for Enhanced Electrocatalysis and Durable Operation

“…The iron species form noticeable clusters whereas the remaining species are relatively uniform in comparison. Reprinted with permission from the Electrochemical Society and IOP Publishing from source (Copyright 2023).…”