Characterisation of defective silicalites
| Autor: | Guido Spano, Vera Bolis, Irene Roggero, Franco Rivetti, Carlo Lamberti, Roberto Buzzoni, G.L. Marra, Gilberto Artioli, Adriano Zecchina, Piero Ugliengo, Silvia Bordiga |
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| Jazyk: | angličtina |
| Rok vydání: | 2000 |
| Předmět: |
Isothermal microcalorimetry
SITES ADSORPTION Hydrogen SURFACE Chemistry Neutron diffraction Caprolactam Cyclohexanone oxime Infrared spectroscopy chemistry.chemical_element General Chemistry CRYSTALLINE chemistry.chemical_compound MOLECULES Adsorption Chemical engineering IR SPECTROSCOPY ISOLATED HYDROXYL TI-SILICALITE Organic chemistry Rearrangement reaction HETEROGENEITY COMPLEXES |
| Popis: | The structure and the adsorptive properties of internal defects in two chemically very pure silicalite samples, characterised by a high and low concentration of defects (internal SiOH nests generated by Si vacancies), are investigated by means of several physical methods (neutron diffraction, IR spectroscopy of adsorbed NH3, microcalorimetry of NH3 adsorption and quantum chemical computation). The role of cooperative effects in hydrogen bonded chains and rings of silanols covering the internal defective nanocavities in influencing the absorptive properties of the material is elucidated. This study provides an explanation of the less hydrophobic character of defective silicalite relative to perfect silicalite and sheds light on the reason why defective silicalite acts as an efficient and selective catalyst for the gas phase Beckman rearrangement reaction where cyclohexanone oxime is converted into caprolactam. |
| Databáze: | OpenAIRE |
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