Synthesis of encapsulated nanoparticules in hollow beta zeolite

Hollow Zeolites with encapsulated nanoparticles (NPs) have recently attracted much attention due to their remarkable advantages as catalytic nanoreactors compared to bulk zeolite supports. Although zeolite shells provide protection against sintering and poisoning, they are usually polycrystalline, fragile and relatively thick. Recently, we succeeded to prepare a series of metal NPs in single hollow zeolite crystals with MFI-type structure by selective dissolution of bulk crystals preliminary loaded with metal precursors (1). The MFI nano-boxes showed remarkable size selectivity in the hydrogenation of toluene but their activity is limited to small substrates because of the small pore opening of the framework (approx.. 0.55 nm) (2). So far, all examples of NPs in hollow single crystals deal with zeolites of MFI-type structure (ZSM-5 and Silicalite-1). In the present work, we report for the first time the preparation of hollow beta zeolite single crystals containing platinum nanoparticles. Beta nano-boxes are prepared by dissolution/recrystallization of CIT-6 crystals, which is a zincosilicate exhibiting the same *BEA structure, based on a modified method (3). Depending on the preparation method, Pt NPs can be located either (i) on the external surface, (ii) in the walls or (iii) inside the cavity of the crystals (4, 5). Materials have been characterized by X-ray diffraction, N2 adsorption and electron microscopy (TEM and SEM). High resolution tomography has also been used to confirm the location of Pt NPs as well as their narrow particle size distribution. Besides structural characterization, the presentation will illustrate the potential of such materials in catalysis by model reactions such as the hydrogenation of substituted aromatics with different sizes. Catalytic results will be discussed in light of adsorption and diffusion studies. (1) S. Li, A. Tuel, J.-L. Rousset, F. Morfin, M. Aouine, L. Burel, F. Meunier, D. Farrusseng, ChemNanoMat. 2(6) (2016) 534. (2) S. Li, A. Tuel, D. Laprune, F. Meunier, D. Farrusseng, Chem. Mater. 27 (2015) 276. (3) K. Iyoki, K. Itabashi, T. Okubo, Chem. Asian J. 2013, 8, 1419. (4) A. R. Morgado Prates, A. Tuel, D. Farrusseng, N. Bats, Fr. Pat. 16/62.460 (2016). (5) A. R. Morgado Prates, A. Tuel, D. Farrusseng, N. Bats, Fr. Pat. 16/62.461 (2016).