(532dk) Gold Nanoparticles with Tailored Size and Their Application As Unusually Stable and Efficient Propylene Epoxidation Catalyst

Gold nanoparticles (AuNPs) are of considerable interest because of their unique chemical and electronic properties.¹The synthesis of these nanoparticles involve a capping agent that provides control over their size, shape, composition, stability, and functionality. The common stabilisers employed in the synthesis are mainly amphiphilic surfactants, ionic liquids, and organic ligands, which are carefully chosen depending upon the application of interest.¹ The chemical and geometric environment around Au can be easily tuned by these bound ligands to modify the active sites and enhance the catalytic performance.

We report a facile synthesis of AuNPs with tunable particle sizes using organic bound phosphine ligands.² The different Au (I) precursors of varying steric hindrance are employed to tune the final size of the AuNPs. A relationship has been discovered that correlates the steric hindrance around bound ligands to the final size of nanoparticles. Additionally, a rapid electrospraying technique using spraying nozzles is also used to produce Au and AgNPs of desired sizes.³ Furthermore, these AuNPs are immobilised onto TS-1 with minimum alteration in the final size.⁴ The catalytic performance of these supported AuNPs is evaluated for the direct gas phase epoxidation of propylene with hydrogen and oxygen, a sustainable route to produce propylene oxide (PO). The results indicate that smaller AuNPs exhibit enhanced catalytic performance based on stability, selectivity, and hydrogen efficiency.

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2. N. Kapil, F. Cardinale, T. Weissenberger, P. Trogadas, T. A. Nijhuis, M. M. Nigra, M.-O. Coppens, Chem. Commun., 2021, 57, 10775.
3. P. Trogadas, N. Kapil, G. M. A. Angel, S. Kühl, P. Strasser, D. J. Brett, M.-O. Coppens, Journal of Materials Chemistry A, 2021, 9, 24283.
4. N. Kapil, T. Weissenberger, F. Cardinale, P. Trogadas, T. A. Nijhuis, M. M. Nigra, M.-O. Coppens, Angew. Chem. Int. Ed., 2021, 60, 18185.