Ni-substituted LaMnO3 perovskites for ethanol oxidation

Abstract

The B-site substitution of LaMnO₃ perovskites by Ni was investigated under the oxidation of ethanol. Proper characterization techniques, including BET surface area measurement, XRD, FTIR, XPS, TPR, O₂-TPD, and FE-SEM experiments were performed to survey the physicochemical properties of perovskites. The results reveal that up to 25% of Mn can be replaced by Ni; beyond this limit, segregated NiO_x can be synthesized. Inserting Ni into the solid solution of perovskite yields unique bridging lattice oxygen sites (Ni–O–Mn) in Ni-doped LaMnO₃. Based on catalytic performance in ethanol oxidation, the Ni–O–Mn sites are likely to promote ethanol conversion and the oxidation of acetaldehyde to CO₂ at low reaction temperatures. The abatement of intermediates over Ni–O–Mn sites is hypothesized and a plausible reaction pathway is proposed. Moreover, the time on-stream testing revealed that the interaction between Ni and Mn is likely to enhance perovskite's thermal stability in ethanol oxidation.