Radicals in carbonaceous residue deposited on mordenite from methanol
| Autor: | Evert J. Ditzel, Justin S. J. Hargreaves, Stephen Sproules, Nicholas A. Spencer |
|---|---|
| Rok vydání: | 2016 |
| Předmět: |
010405 organic chemistry
Renewable Energy Sustainability and the Environment Radical Inorganic chemistry General Chemistry Coke 010402 general chemistry Photochemistry 01 natural sciences Mordenite Spectral line 0104 chemical sciences law.invention Catalysis chemistry.chemical_compound chemistry law General Materials Science Methanol Electron paramagnetic resonance Hyperfine structure |
| Zdroj: | Journal of Materials Chemistry A. 4:7036-7044 |
| ISSN: | 2050-7496 2050-7488 |
| DOI: | 10.1039/c6ta01053a |
| Popis: | It is shown that control of the degree of coking can lead to the observation of hyperfine structures in the carbonaceous residues deposited from methanol over mordenite (H-MOR) at temperatures relevant to the conversion of methanol to hydrocarbons. EPR measurements of the catalyst samples at various times on stream have been recorded, with a rich hyperfine splitting pattern observed in the early stages of the reaction. Interpretation of the EPR data with the aid of density functional theoretical calculations has afforded the first definitive assignment of the radical cations formed in high temperature coke. The results detail a shortlist of six species: 2,3/2,6/2,7-dimethylnaphthalenium, 2,3,6-trimethylnaphthalenium, 2,3,6,7-tetramethylnaphthalenium, and anthracenium radical cations whose proton hyperfine splitting profiles match the experimental spectra; 2,3,6,7-tetramethylnaphthalenium showed the best agreement. The observation of these particular isomers of polymethylnaphthalene suggest the formation of more highly branched polyaromatic species is less likely within the confines of the H-MOR 12-membered ring channel. These radicals formed when the catalyst is active may constitute key intermediates in the conversion of methanol to light olefins. |
| Databáze: | OpenAIRE |
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