Browsing by Author "Derouane, E. G."
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- Mild liquid-phase Friedel-Crafts acylation of heteroaromatic compounds over zeolite BetaPublication . Álvaro, V. F. D.; Brigas, Amadeu; Derouane, E. G.; Lourenço, J. P.; Santos, Bruna S.Heteroaromatic compounds, such as thiophenes, pyrroles and furans, were acylated using zeolite Beta, with and without modifications, and acetic anhydride. Amenable conditionswere found to carry out these acylations in high yield, sometimes in a very short time (10 min). Indium modified catalyst have provided a way of attaining good yields in the acylation of pyrrole.
- Study of catalytic properties of SAPO-40Publication . Lourenço, J. P.; Ribeiro, M. F.; Ribeiro, F. R.; Rocha, J.; Gabelica, Z.; Dumont, N.; Derouane, E. G.A series of SAPO-40 samples with Si atomic fraction from 0.06 to 0.12 has been synthesised. The study of their catalytic properties has been evaluated by comparison with SAPO-37, USHY and mordenite, using as model reaction the cracking of n-heptane. The catalytic activity of SAPO-40 samples depends on the Si content, and is probably associated with the non-uniform distribution of silicon. SAPO-40 showed a stronger acidity than SAPO-37 with a similar Si content. SAPO-40 is more resistant to deactivation by coke than the studied mordenite sample. Its selectivity for cracking products is comparable to USHY, but hydrogen transfer is lower for SAPO-40 than for USHY and mordenite.
- Thermal and hydrothermal stability of silicoaluminophosphate SAPO-40Publication . Lourenço, J. P.; Ribeiro, M. F.; Ribeiro, F. R.; Rocha, J.; Gabelica, Z.; Derouane, E. G.Thermal and hydrothermal stability of SAPO-40 were studied by X-ray powder diffraction (XRD) and magic-angle spinning nuclear magnetic resonance (MAS-NMR). For the X-ray study, the hydrothermal treatments were carried out, in situ, in a high-temperature chamber. The SAPO-40 structure shows a remarkable stability to high temperatures under both dry and humid air. At high temperatures a reorganisation of silicon occurs, but the long-range order is only lost above ca. 1000°C. Changes in the XRD pattern induced by water at room temperature are completely reversible upon re-heating at 200°C, as well as the changes in the coordination and local environments of aluminium and phosphorus observed by NMR. For silicon however, some changes, that are observed upon hydration, remain after dehydration.