A-site cations tailoring the activity of LnMnO3 perovskites for CO and propane oxidation

Abstract

To understand the role of A-site cations of perovskites on the reactivity, the LnMnO3 perovskites (Ln = La, Nd, Sm) with varied A-site cations were prepared by a facile glycine combustion method and evaluated for CO and propane oxidation. The activity for both reactions followed the trend: NdMnO3 > SmMnO3 > LaMnO3, demonstrating that lanthanide cations at A sites significantly affect the catalytic performance. Combined with Fourier transmission infrared spectra, temperature programmed reduction and desorption techniques, it was revealed that both the strength of Mn–O bonds and the adsorption of reactants played crucial roles on the activity for CO oxidation and C3H8 combustion on the LnMnO3. The adsorption of the reactants was responsible for the higher activity on the NdMnO3 than on the SmMnO3, while the strength of Mn–O bonds for the higher activity on the SmMnO3 than on the LaMnO3. The NdMnO3 possessed both weak Mn–O bonds and favorable adsorption of the reactants achieved the highest activity for CO oxidation and C3H8 combustion. The best NdMnO3 catalyst achieved CO and propane complete conversion at 160 and 360 °C, 90 and 60 °C lower than the LaMnO3, respectively.