A critical review on deactivation dynamics in methane combustion catalysts: Challenges and innovations for palladium-based systems

Palladium-based catalysts are pivotal for catalytic methane combustion, crucial for decarbonization efforts. Yet, industrial use is limited by three critical deactivation mechanisms: water inhibition, thermal sintering, and sulfur poisoning. This review synthesizes mechanistic insights and mitigation strategies holistically. Water inhibition below 500°C arises from hydroxyl species blocking active Pd sites, reversible via hydrophobic supports (e.g., zeolites) or oxygen- mobile promoters (Ce-Zr oxides) to enhance lattice oxygen mobility. Sintering from PdO agglomeration above 300°C, is countered by core-shell architectures (e.g., Pd-CeOx@SiO₂) and strong metal-support interactions with reducible oxides (CeO₂, perovskites). Sulfur poisoning via sulfate formation is mitigated through sulfur-resistant perovskites and dynamic Pd-perovskite frameworks that prevent PdSO₄ accumulation. Key innovations include engineered bimetallic alloys (Pd-Pt) to stabilize active Pd⁰ states, hydrophobic coatings to limit hydroxyl adsorption, and sorbents (CaO) for in situ water removal. Advanced characterization (AP-XPS, DRIFTS) reveals water’s dual role in hydroxylation and sulfur mobility, while regeneration strategies (pulsed redox cycles) extend catalyst lifetimes. By integrating material design, mechanistic understanding, and operational optimization, this work establishes a roadmap for durable Pd-based catalysts, advancing methane utilization in turbines, vehicles, and industrial systems. These breakthroughs address a critical gap in catalysis science, enabling efficient methane abatement to support global