Perovskite-supported palladium for methane oxidation - structure-activity relationships.

Area of Science:

• Materials Science
• Catalysis
• Surface Chemistry

Background:

• Palladium (Pd) is essential for methane oxidation catalysis.
• Perovskite oxides stabilize palladium as PdO, crucial for activity.
• Pd's oxidation and coordination states influence catalytic performance.

Purpose of the Study:

• Review the impact of perovskite composition on Pd states.
• Investigate Pd's influence on methane oxidation catalysis.
• Explore Pd stabilization and activation in perovskites.

Main Methods:

• X-ray absorption near edge structure (XANES) spectroscopy to determine Pd states.
• Synthesis and characterization of perovskite-based catalysts (LaMnO3, La(Fe,Pd)O3).
• Evaluation of catalytic activity for methane oxidation.

Main Results:

• Pd substitution in Fe and Co perovskites did not alter activity.
• Palladium on LaMnO3 is surface-exposed, enhancing methane oxidation.
• Cyclic activation of Pd in La(Fe,Pd)O3 under redox conditions boosts activity.

Conclusions:

• Perovskite composition critically affects palladium's catalytic role.
• Surface exposure of Pd on LaMnO3 is key for methane oxidation.
• Pd occupancy in perovskite B-cation sites enables cyclic activation and protection, enhancing catalytic performance for applications like three-way catalysts.