Scalable synthesis of palladium nanoparticle catalysts by atomic layer deposition
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Atomic layer deposition (ALD) was used to produce Pd/Al2O3 catalysts using sequential exposures of Pd(II) hexafluoroacetylacetonate and formalin at 200 °C in a fluidized bed reactor. The ALD-prepared Pd/alumina catalysts were characterized by various methods including hydrogen chemisorption, XPS, and TEM, and compared with a commercially available 1 wt% Pd/alumina catalyst, which was also characterized. The content of Pd on alumina support and the size of Pd nanoparticles can be controlled by the number of ALD-coating cycles and the dose time of the Pd precursor. One layer of organic component from the Pd precursor remained on the Pd particle surface. The ALD 0.9 wt% Pd/alumina had greater active metal surface area and percent metal dispersion than the commercial 1 wt% Pd/alumina catalyst. The ALD and commercial catalysts were subjected to catalytic testing to determine their relative activities for glucose oxidation to gluconic acid in aqueous solution. The ALD 0.9 wt% Pd/alumina catalyst had comparable activity as compared to the commercial 1 wt% Pd catalyst. No noticeable amount of Pd leaching was observed for the ALD-prepared catalysts during the vigorously stirred reaction.
KeywordsPalladium (Pd) Nanoparticle (NP) Atomic layer deposition (ALD) Fluidized bed reactor Glucose oxidation
The authors thank Andrew S. Cavanagh for the XPS analysis, Fred Luiszer for providing the ICP-MS analysis, as well as Brittany J. Michael for the assistance with part of the glucose oxidation tests. The authors also thank Prof. J. Will Medlin for helpful discussions.
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