Supported Catalyst Deactivation by Decomposition into Single Atoms Is Suppressed by Increasing Metal Loading

Area of Science:

• Materials Science
• Catalysis
• Nanotechnology

Background:

• Supported precious metal catalysts are crucial for industrial processes but suffer activity loss at high temperatures.
• This deactivation is typically attributed to nanoparticle sintering, where small particles merge into larger ones.
• Current strategies involve using excess noble metals to compensate for activity loss over the catalyst's lifetime.

Purpose of the Study:

• To investigate novel deactivation mechanisms in supported precious metal catalysts beyond traditional nanoparticle sintering.
• To understand the role of particle size, loading, and support interactions in catalyst deactivation at high temperatures.
• To develop a quantitative model explaining catalyst stability based on particle density and support characteristics.

Main Methods:

• Utilized colloidal nanocrystals to independently control particle size and loading on catalyst supports.
• Exposed catalysts to high-temperature environments to observe deactivation processes.
• Employed advanced characterization techniques to analyze nanoparticle behavior and identify deactivation pathways.
• Developed a quantitative statistical model to correlate catalyst performance with particle density and support defect sites.

Main Results:

• Discovered a novel deactivation mechanism: high-temperature nanoparticle decomposition into inactive single atoms.
• Observed rapid activity loss, with significant deactivation occurring within ten minutes.
• Demonstrated that this decomposition pathway is highly dependent on particle density and the concentration of support defect sites.
• Showed that higher particle densities can enhance catalyst stability for specific reactions, contrary to sintering expectations.

Conclusions:

• Nanoparticle decomposition into single atoms is a critical, rapid deactivation pathway for supported precious metal catalysts at high temperatures.
• Catalyst deactivation is not solely due to sintering but also influenced by particle decomposition, which is sensitive to particle loading and support properties.
• Optimizing particle density and understanding support defect sites are key strategies for designing more stable and efficient high-temperature catalysts.