Efficient combustion of low concentration methane over perovskite/BN-La: Enhanced catalytic performance and fundamental kinetic analysis

Abstract

Catalytic combustion is an efficient method for removing low concentration methane from exhaust gases, with the key challenge being the development of highly effective catalysts. This study develops a composite powder perovskite MFC/BN using BN as a high thermal conductivity carrier and La as an additive for efficient methane combustion. This catalyst can achieve complete methane combustion at 455.7 °C, and run efficiently for over 25 h at 800 °C (methane conversion rate > 97 %). The structural and chemical characterizations (XRD, BET, SEM, and XPS) reveal an increased specific surface area (28.8 m²/g) and Mn⁴⁺ species (46.31 %). The excellent thermal conductivity of BN carrier improves heat transfer while reducing catalyst aging and sintering, and its interaction with MFC decreases perovskite grain size and increases the specific surface area. La can induce the formation of more Mn⁴⁺, Fe³⁺ and O_lat species on the surface. Then, kinetic analysis demonstrates the pre-exponential factor (1.42 × 10⁹ mol·g⁻¹·s⁻¹·kPa⁻¹) and reaction activation energy (73.6 kJ/mol) in the reaction with a power function, and clarifies the relationship between the reactant and the catalyst surface. The mechanism shows that methane dehydrogenation and oxidation are rate-controlling steps, with BN and La facilitating CH₄ dehydrogenation to form CH₃, CH₂, and CHO intermediates.