Coking- and sintering-resistant palladium catalysts achieved through atomic layer deposition

Area of Science:

• Materials Science
• Chemical Engineering
• Catalysis

Background:

• Heterogeneous catalysts, particularly supported metal nanoparticles (NPs), are prone to deactivation via coking and sintering at high temperatures.
• Developing robust catalysts is crucial for efficient industrial chemical processes.

Purpose of the Study:

• To investigate the efficacy of alumina (Al(2)O(3)) overcoating on palladium (Pd) nanoparticles (NPs) to enhance catalyst stability.
• To evaluate the impact of this protective layer on catalyst performance in high-temperature reactions.

Main Methods:

• Palladium NPs were overcoated with 45 layers of alumina using atomic layer deposition (ALD) at 200°C.
• The ALD process involved alternating exposures to trimethylaluminum and water.
• Catalyst performance was tested in the oxidative dehydrogenation of ethane to ethylene at 650°C.

Main Results:

• Thermogravimetric analysis revealed less than 6% coke formation on ALD Al(2)O(3) overcoated catalysts compared to uncoated ones after 1 hour of reaction.
• Scanning transmission electron microscopy confirmed no significant morphology changes in the overcoated catalysts after 28 hours of reaction at 675°C.
• Ethylene yield was improved across all ALD Al(2)O(3) overcoated Pd catalysts.

Conclusions:

• Alumina overcoating via ALD effectively mitigates deactivation by coking and sintering in supported palladium catalysts.
• This surface modification strategy enhances catalyst durability and improves product yield in high-temperature heterogeneous catalysis, specifically for ethane to ethylene conversion.