A citric acid-assisted deposition strategy to synthesize mesoporous SiO2-confined highly dispersed LaMnO3 perovskite nanoparticles for n-butylamine catalytic oxidation

Abstract

Catalytic oxidation can efficiently eliminate nitrogen-containing volatile organic compounds (NVOCs) and suppress the generation of toxic NO_x in order to avoid secondary pollution. In this study, mesoporous SiO₂-confined LaMnO₃ perovskite nanoparticles with high dispersion were successfully prepared by a citric acid-assisted deposition method (LMO/SiO₂-SD) and tested for the oxidation of n-butylamine. The method utilized the synergistic effect of abundant active hydroxyl groups existing on the SiO₂ gel surface and citric acid, rendering the metal ions more uniformly scattered on the SiO₂ surface. Strikingly, the LMO/SiO₂-SD sample exhibited the optimum catalytic performance (T₉₀ at 246 °C) and the highest N₂ selectivity, which was mainly ascribed to its abundant surface acid sites, superior low-temperature reducibility and higher ratio of surface Mn⁴⁺ species. The apparent activation energy (E_a) for n-butylamine oxidation over LMO/SiO₂-SD sample was 29.0 kJ mol⁻¹. Furthermore, the reaction mechanism of n-butylamine oxidation was investigated by in situ FITR and a reasonable reaction route for n-butylamine oxidation over the LMO/SiO₂-SD sample was proposed.