| Autor: |
Bignami GPM; School of Chemistry, EaStCHEM and Centre of Magnetic Resonance, University of St. Andrews , North Haugh, St. Andrews, Fife KY16 9ST, United Kingdom., Dawson DM; School of Chemistry, EaStCHEM and Centre of Magnetic Resonance, University of St. Andrews , North Haugh, St. Andrews, Fife KY16 9ST, United Kingdom., Seymour VR; School of Chemistry, EaStCHEM and Centre of Magnetic Resonance, University of St. Andrews , North Haugh, St. Andrews, Fife KY16 9ST, United Kingdom., Wheatley PS; School of Chemistry, EaStCHEM and Centre of Magnetic Resonance, University of St. Andrews , North Haugh, St. Andrews, Fife KY16 9ST, United Kingdom., Morris RE; School of Chemistry, EaStCHEM and Centre of Magnetic Resonance, University of St. Andrews , North Haugh, St. Andrews, Fife KY16 9ST, United Kingdom., Ashbrook SE; School of Chemistry, EaStCHEM and Centre of Magnetic Resonance, University of St. Andrews , North Haugh, St. Andrews, Fife KY16 9ST, United Kingdom. |
| Abstrakt: |
The great utility and importance of zeolites in fields as diverse as industrial catalysis and medicine has driven considerable interest in the ability to target new framework types with novel properties and applications. The recently introduced and unconventional assembly, disassembly, organization, reassembly (ADOR) method represents one exciting new approach to obtain solids with targeted structures by selectively disassembling preprepared hydrolytically unstable frameworks and then reassembling the resulting products to form materials with new topologies. However, the hydrolytic mechanisms underlying such a powerful synthetic method are not understood in detail, requiring further investigation of the kinetic behavior and the outcome of reactions under differing conditions. In this work, we report the optimized ADOR synthesis, and subsequent solid-state characterization, of 17 O- and doubly 17 O- and 29 Si-enriched UTL-derived zeolites, by synthesis of 29 Si-enriched starting Ge-UTL frameworks and incorporation of 17 O from 17 O-enriched water during hydrolysis. 17 O and 29 Si NMR experiments are able to demonstrate that the hydrolysis and rearrangement process occurs over a much longer time scale than seen by diffraction. The observation of unexpectedly high levels of 17 O in the bulk zeolitic layers, rather than being confined only to the interlayer spacing, reveals a much more extensive hydrolytic rearrangement than previously thought. This work sheds new light on the role played by water in the ADOR process and provides insight into the detailed mechanism of the structural changes involved. |
