Preparation, characterization and catalytic application of hierarchically porous LaFeO3 from a pomelo peel template

Abstract

Hierarchically porous LaFeO₃ perovskites are synthesized through a facile process by using pomelo peel as a biotemplate. The samples are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), N₂ adsorption–desorption analyses, Fourier-transform infrared spectroscopy (FT-IR), thermogravimetric/differential thermal analysis (TG–DTA) and transmission electron microscopy (TEM). The results show that pomelo peel templated LaFeO₃ perovskites successfully replicate the structural features of pomelo peel from the macro- to the nanoscale, resulting in a hierarchically porous structure. Moreover, the framework is assembled from plenty of nanoparticles, and there exist a large number of voids between the nanoparticles in the framework. The surface area and average pore diameter of pomelo peel templated-LaFeO₃ are 26.7 m² g⁻¹ and 21 nm, respectively, which are larger than bulk LaFeO₃. The catalytic performances of the as-prepared samples for the NO + CO reaction are tested. The templated LaFeO₃ exhibits better catalytic activity, with NO conversion achieving 95% at 324 °C and CO conversion achieving 94% at 350 °C. This can be assigned to its larger specific surface area and hierarchically porous structure, which can lead to more active sites and promote the diffusion of reactants in the reaction.