2020 Virtual AIChE Annual Meeting

(691g) Redispersion of Pt Nanoparticles to Single Atoms over Reducible Metal Oxides

Authors

Wang, Y. - Presenter, University of Delaware
Vlachos, D. - Presenter, University of Delaware - Catalysis Center For Ener
Fu, J., University of Delaware
Zheng, W., University of Delaware
Single-atom catalysts (SACs) have attracted increasing scientific attention in recent years due to their full metal atom utilization and the potential for different activity and selectivity. Several chemical and physical methods have been reported for SAC synthesis.1 However, most of the methods generate low-loading SACs to avoid sintering or agglomeration due to their intrinsic thermal instability.2 Redispersion of metal nanoparticles (NPs) is important to increase metal dispersion and atom efficiency with maintaining high metal loading. Recently, several cases have demonstrated that high loading NPs can be redispersed to atoms or small clusters using various methods, such as oxidation/pyrolysis and atom trapping at high temperatures (> 900 °C),1 and oxychlorination.3 Energy consumption or hardly-removable ligands on the catalysts are drawbacks in these approaches.

Redispersion via iodomethane (CH3I) treatment is a relatively new approach. Carbon supported metal NPs have been dispersed to single atoms and clusters.4-6 Until now, redispersion of Pt NPs on reducible metal oxides, such as TiO2, has not been reported. Herein, we present an efficient approach to redisperse TiO2 supported Pt NPs to SACs through an iodo-based treatment. Extensive characterization is used, including IR, AP-XPS, XAS, and microscopy to demonstrate the redispersion. Furthermore, we use a number of probe reactions to showcase their unique catalytic performance. Specifically, we show that the redispersed catalysts remain single Pt atoms after H2 reduction and present higher selectivity in hydrodeoxygenation and selective hydrogenation reactions compared to Pt NPs.

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  2. Fu J. et al. Nat. Catal., doi. 10.1038/s41929-41020-40445-x (2020).
  3. Morgan K. et al. ACS Catal. 5, 3430-3445 (2015).
  4. Sá J. et al. Angew. Chem. Int. Ed. 50, 8912-8916 (2011).
  5. Morgan K. et al. Catal. Sci. Technol. 4, 729 (2014).
  6. Feng S. et al. Nat. Commun. 10, 5281 (2019).