Anchoring PdO_x clusters on defective alumina for improved catalytic methane oxidation

Area of Science:

• Catalysis
• Materials Science
• Surface Chemistry

Background:

• Palladium (Pd) active centers in high-temperature catalysis often deactivate due to growth and aggregation.
• Controlling the size and distribution of Pd species is crucial for catalyst longevity and performance.

Purpose of the Study:

• To investigate the use of defective alumina (Al₂O_3-x) as a support to stabilize Pd active centers for methane oxidation.
• To elucidate the mechanisms of methane oxidation on different Pd species (single atoms, clusters, nanoparticles) using defective alumina.

Main Methods:

• Operando spectroscopy to monitor catalyst evolution under reaction conditions.
• Density functional theory (DFT) calculations to understand reaction mechanisms.
• Catalytic testing of Pd supported on defective (Al₂O_3-x) and conventional (Al₂O₃) alumina.

Main Results:

• Defective alumina (Al₂O_3-x) effectively anchors Pd atoms, suppressing cluster growth.
• Pd clusters on Al₂O_3-x demonstrated superior methane oxidation activity and stability.
• Pd clusters showed high dispersion, a significant Pd²⁺ content, and resistance to deactivation by common byproducts.

Conclusions:

• Defect engineering of non-reducible supports like alumina can stabilize active metal centers, preventing deactivation.
• Pd clusters on defective alumina offer a promising catalytic system for methane oxidation with enhanced durability.
• This approach has broad implications for designing stable catalysts for various industrial oxidation and hydrogenation reactions.