Atomic Layer Deposition Overcoating: Tuning Catalyst Selectivity for Biomass Conversion

• Published in: Angewandte Chemie International Edition 2014-11, Vol.53 (45), p.12132-12136
• Main Authors: Zhang, Hongbo, Gu, Xiang-Kui, Canlas, Christian, Kropf, A. Jeremy, Aich, Payoli, Greeley, Jeffrey P., Elam, Jeffrey W., Meyers, Randall J., Dumesic, James A., Stair, Peter C., Marshall, Christopher L.
• Format: Article
• Language: English
• Subjects: atomic layer deposition; Biomass; Catalysis; catalyst selectivity; Catalysts; Deposition; Furans; Furfural; hydrogenation; Nanoparticles; Palladium; Selectivity; Terraces
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.201407236

The terraces, edges, and facets of nanoparticles are all active sites for heterogeneous catalysis. These different active sites may cause the formation of various products during the catalytic reaction. Here we report that the step sites of Pd nanoparticles (NPs) can be covered precisely by the atomic layer deposition (ALD) method, whereas the terrace sites remain as active component for the hydrogenation of furfural. Increasing the thickness of the ALD‐generated overcoats restricts the adsorption of furfural onto the step sites of Pd NPs and increases the selectivity to furan. Furan selectivities and furfural conversions are linearly correlated for samples with or without an overcoating, though the slopes differ. The ALD technique can tune the selectivity of furfural hydrogenation over Pd NPs and has improved our understanding of the reaction mechanism. The above conclusions are further supported by density functional theory (DFT) calculations. Terrace versus step sites: Atomic layer deposition (ALD) overcoating was applied to cover the step sites of Pd nanoparticles with alumina, whereas the terrace sites remained as the active component for furfural hydrogenation. The modified catalyst exhibited an increased selectivity to furan, showing that this technique can be used to tune the catalytic properties of Pd nanoparticles.