Ag+-Exchanged LSX (Ag-LSX: Ag96Al96Si96O384⋅n H2O), a large pore low silica analogue (Si/Al=1.0) of faujasite, was prepared and post-synthetically modified using pressure and temperature in the presence of various pore-penetrating fluids. Using high-resolution synchrotron X-ray powder and single crystal diffraction we derive structural models of the as-prepared and post-synthetically modified Ag-LSX materials. In the as-prepared Ag-LSX model, we located 96 silver cations and 245 H2O molecules distributed over seven and five distinctive sites, respectively. At 1.4(1) GPa pressure and 150 °C in ethanol the number of silver cations within the pores of Ag-LSX is reduced by ca. 47.4 %, whereas the number of H2O molecules is increased by ca. 40.8 %. The formation of zero-valent silver nanoparticles deposited on Ag-LSX crystallites depends on the fluid present during pressurization. Ag-nanoparticle-Ag-zeolite hybrid materials are recovered after pressure release and shown to have different chemical reactivity when used as catalysts for ethylene epoxidation.
Bibliographical noteFunding Information:
This work was supported by the Global Research Laboratory (NRF-2009-00408) and National Research Laboratory (NRF-2015R1A2A1A01007227) programs of the Korean Ministry of Science, ICT and Planning (MSIP). We also thank the supports by NRF-2016K1A4A3914691 and NRF-2016K1A3A7A09005244 grants. Experiments using X-ray synchrotron radiation were supported by the Pohang Accelerator Laboratory (PAL). The JEOL 2100F is supported by the Office of Research at the University of South Carolina.
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All Science Journal Classification (ASJC) codes
- Organic Chemistry