| Autor: |
Joaquim Vital, A.P. Esculcas, João Rocha, A. Severino, L.S. Lobo |
| Rok vydání: |
1996 |
| Předmět: |
|
| Zdroj: |
Applied Catalysis A: General. 142:255-278 |
| ISSN: |
0926-860X |
| DOI: |
10.1016/0926-860x(96)00091-9 |
| Popis: |
The liquid phase isomerisation of α-pinene was studied on a number of zeolite catalysts at 150°C. The primary reaction products were camphene, tricyclene and p -menthadienes. Catalyst samples with lattice Si/Al ratios ranging from 1.46 to ca. 200 were prepared by hydrothermal treatment of zeolites Y and X. The nature of extra-framework aluminium species was investigated by 27 Al-MAS-NMR spectroscopy. For high values of N Al (number of framework aluminium atoms per unit cell) extra-lattice aluminium (EFAL) species have a promoting effect on the catalytic activity. On the other hand, for the highly dealuminated samples the catalytic activity decreases with N Al . However it does not seem to become zero for zero Bronsted acidity, suggesting that Lewis acid sites are also active on α-pinene isomerisation. Selectivity towards camphene is also strongly affected by EFAL species, decreasing at high values of N Al and increasing for the catalyst samples with high EFAL content. The different distribution of EFAL species in the catalysts prepared at different temperatures would cause this effect on selectivity. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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