Highly Active Oxidation Catalysts through Confining Pd Clusters on CeO₂ Nano-Islands

Area of Science:

• Materials Science
• Catalysis
• Nanotechnology

Background:

• Cerium dioxide (CeO2)-supported noble metal clusters are effective catalysts but prone to deactivation via metal atom dispersion under oxidizing conditions.
• Maintaining atomic dispersion of noble metals on supports is crucial for catalytic activity but challenging under reaction conditions.

Purpose of the Study:

• To rationally adjust the noble metal cluster formation threshold using a mixed CeO2-Al2O3 support.
• To investigate the role of support composition in stabilizing small noble metal clusters for low-temperature CO oxidation.
• To develop a strategy for efficient noble metal utilization in heterogeneous catalysis.

Main Methods:

• Synthesis of mixed CeO2-Al2O3 supports.
• Preparation of low-loading palladium (Pd) catalysts (0.5 wt%).
• Characterization using in situ/operando techniques to study Pd cluster formation and stability.
• Evaluation of catalytic performance for CO oxidation at low temperatures.

Main Results:

• A mixed CeO2-Al2O3 support facilitated the in situ formation of small Pd clusters at low Pd loading.
• Preferential Pd location on CeO2 islands promoted high local metal concentration and prevented redispersion.
• The structured support confined Pd mobility, maintaining high CO oxidation activity at low temperatures.
• The catalyst demonstrated enhanced stability and activity compared to traditional supports.

Conclusions:

• Mixed CeO2-Al2O3 supports effectively stabilize small noble metal clusters, enhancing catalytic performance.
• This approach offers a method to rationally control catalyst structure and prevent deactivation.
• The strategy of using mixed oxide supports to confine metal mobility is transferable to other catalytic systems and reactions.