Effects of LaFeO<sub>3</sub> Morphology on Oxygen Species and Chemical Looping Partial Oxidation of Methane
Henglong Li, Ping Li, Min Lin, Xing Zhu
Abstract
The design of oxygen carriers is essential for the chemical looping partial oxidation of methane (CL-POM) in syngas production. LaFeO 3 is a promising oxygen storage material, but the impact of its morphology on the reaction characteristics and mechanisms in CL-POM remains unclear. Herein, we synthesized and characterized LaFeO 3 samples with diverse morphologies (cube, porous microsphere, irregular nanoparticle, and polyhedron) to explore how morphology governs crystal plane exposure, oxygen vacancy formation, and oxygen migration. Results showed that cubic LaFeO 3 not only achieved outstanding oxygen storage capacity (4.18 mmol/g), 2.5 times that of the other three samples combined (1.64 mmol/g), but also demonstrated superior methane reactivity with good low-temperature activity (initial reaction temperature of 500 °C) and the highest methane conversion (78.26% at 750 °C). This impressive performance is due to the synergy between oxygen vacancies and the (110) crystal plane, which optimizes oxygen release and enhances methane adsorption and dissociation. DFT calculations further confirmed that the (110) plane has lower energy barriers for reaction processes than the (100) plane, and more oxygen vacancies enhance reactivity and oxygen migration. This work underscores the pivotal role of LaFeO 3 morphology in advancing the design of oxygen storage materials and a redox catalyst.