Platinum
group metals (PGMs) are widely used for exhaust emission
abatement. Sintering during high-temperature emission control conditions
decreases noble metal utilization efficiency. Efficient use of scarce
noble metals requires sinter-resistant catalysts. Here, we extend
an approach to synthesize catalysts consisting of platinum nanoparticles
encapsulated in a mixture of cerium and aluminum oxides (Pt@Al2O3–CeO2). We tested the activity
of this catalyst toward carbon monoxide, propene, and propane oxidation,
chosen as model oxidation reactions for emission control catalysts.
Pt@Al2O3–CeO2 catalysts demonstrated
similar activity and stability upon aging as the comparison system
without ceria, Pt@Al2O3, while maintaining small
Pt nanoparticles and ceria crystallites. Additionally, we studied
the influence of various thermal treatments on the carbon monoxide
(CO) oxidation activity and determined that a steam treatment can
activate the low-temperature CO oxidation activity of Pt@Al2O3–CeO2. Scanning transmission electron
microscope–energy-dispersive X-ray spectroscopy (STEM–EDS)
analysis revealed that thermal treatments led to the colocation of
Pt and CeO2, and temperature-programmed reduction analysis
revealed that the steam treatment specifically enhanced CO oxidation
activity through surface reduction of the CeO2. In summary,
we demonstrate the versatility of this encapsulation approach to generate
mixed metal-oxide supports with improved metal–support interactions
without hindering the nanoparticle stability.