Barium Substituted Lanthanum Manganite Perovskite for CO₂ Reforming of Methane

Abstract

Barium substituted lanthanum manganite La1–xBaxMnO3 (x = 0.10–0.50) of a single phase perovskite structure was used as catalysts for CO2 reforming of CH4 for the first time. The optimal level of Ba substitution (Ba/Mn = 0.10, 0.15) produced La1–xBaxMnO3 of high surface area, uniform particle dispersion, and highly ordered pores. The optimally substituted perovskite catalysts showed much improved reducibility of Mn3+/Mn4+ to Mn2+ to provide oxygen vacancies and rapid migration of lattice oxygen from the bulk toward the surface. The ability of donating lattice oxygen to the catalytic cycle seems responsible for the facilitated decomposition and dissociation of CH4 and CO2, which led to high conversions, excellent syngas selectivity, and stability with little coke formation. The addition of oxygen to the dry reforming reaction showed improved conversion and selectivity to syngas by making catalysts less prone to coke formation. To the best of our knowledge, the results represent the first example of Mn-based reforming catalysts that perform better than more common Ni-based catalysts of the same structure.