Advances in the influencing factors and reaction mechanisms of Pd-based supported catalysts for catalytic methane combustion

Abstract

Methane (CH₄) is a valuable clean energy source, but it is the second-most significant greenhouse gas after CO₂. Given the relatively low concentration of CH₄ in the atmosphere, its elimination and treatment present considerable challenges. In this case, catalytic combustion technology is currently an effective way to reduce the emission of lean CH₄ into the atmosphere. The essential factor for the success of this technology lies in the design and development of efficient CH₄ combustion catalysts. Palladium (Pd)-based supported catalysts have attracted significant attention from researchers because of their excellent low-temperature performance. Accordingly, a deeper comprehension of various factors affecting the performance of Pd-based supported catalysts and reaction mechanisms underlying catalytic CH₄ combustion would enable the development of Pd-based supported catalysts with high stability, high activity, and excellent anti-poisoning properties. This study presented a detailed and comprehensive review of the factors that affect the catalytic performance of Pd-based supported catalysts, such as the particle size and oxidation state of Pd species; selection of auxiliary components; and the acidity, hydrophobicity, redox performance, and morphology of the carrier. Different reaction mechanisms for catalytic CH₄ combustion reactions, including the Mars–van Krevelen (MvK), Langmuir–Hinshelwood (L–H), Eley–Rideal (E–R), and mixed mechanisms, were also explored in detail. Finally, the challenges and future development tendencies of Pd-based supported catalysts in CH₄ combustion were summarized and predicted.