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.
All Science Journal Classification (ASJC) codes
- Organic Chemistry