One-step hydrothermal synthesis of LaFeO3 perovskite for methane steam reforming

Abstract

This work describes the synthesis of LaFeO3 oxide, using a one-step hydrothermal synthesis route, to obtain a solid with useful superficial, morphological and textural properties for applications in steam methane reforming reaction. The synthesis process starts from the corresponding metal nitrates of lanthanum and iron dissolved in deionized water in well-defined concentration, and the dissolution of KOH as mineralizing agent. The reaction is developed in a Teflon-lined stainless steel autoclave at 300 °C for 14 days. The composition and surface area were determined with X-ray fluorescence and nitrogen adsorption isotherms, confirming the basic stoichiometry of oxide and a high active area. The crystalline structure was evaluated with X-ray diffraction analysis, showing a pure orthorhombic perovskite phase. Temperature programmed reduction results show the development of three single steps at different temperatures, kinetically detectable and related with reduction of component oxides. Scanning and transmission electron microscopy results, showed a remarkable degree of crystallization, favoring a specific morphology as result of the low consolidation temperature of the perovskite phase. The catalytic test, analyzed by means of steam methane reforming action, performed along 240 h on stream, reveals a light deactivation rate, decreasing progressively 7.1 % until 60 % of methane conversion, indicating the improved morphological and surface characteristics of solid for potential applications.