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@Al 2 O 3 –CeO 2 ). We tested the activity of this catalyst toward carbon monoxide, propene, and propane oxidation, chosen as model oxidation reactions for emission control catalysts. Pt@Al 2 O 3 –CeO 2 catalysts demonstrated similar activity and stability upon aging as the comparison system without ceria, Pt@Al 2 O 3, 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@Al 2 O 3 –CeO 2 . Scanning transmission electron microscope–energy-dispersive X-ray spectroscopy (STEM–EDS) analysis revealed that thermal treatments led to the colocation of Pt and CeO 2, and temperature-programmed reduction analysis revealed that the steam treatment specifically enhanced CO oxidation activity through surface reduction of the CeO 2 . 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.
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Stone et al. (2023) studied this question.
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