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Evidence of a solvent screen effect affecting the redox properties of Co(II) io...
Gabelica, Z.; Louati, A.; Borges, C.; Ribeiro, M. F.; Lourenço, J. P.; Murphy, D. M.Cyclic voltammetric experiments of framework Co(II) ions in three different CoAPO structures have provided evidence for a screening effect created by solvent or template molecules which results in a facile oxidation (and a difficult reduction) of the Co(II) ions incorporated into the most open (the less strained) structures. An apparent contradiction of these findings with respect to theoretical expectations is...
Efficient co-templating roles of amines and amides admixed with alkylammonium s...
Borges, C.; Ribeiro, M. F.; Henriques, C.; Duarte, M.; Lourenço, J. P.; Gabelica, Z.Two different aluminophosphate structures were synthesised in aqueous media using as main template methylamine (MA), directly added, or generated in situ from methylformamide (MF). Both involve novel AlPO4-n topologies that undergo structural transformations upon template removal, yielding above 350°C microporous thermostable materials with interesting properties. Tetraalkylammonium (TEA) cations were used opti...
Synthesis and acidity characterization of CoAPO-37
Costa, C. S.; Lourenço, J. P.; Henriques, C.; Antunes, A. P.; Ribeiro, F. R.; Ribeiro, M. F.; Gabelica, Z.A well-crystallized sample of CoAPO-37 was prepared. The incorporation of cobalt in the FAU structure framework was indirectly shown by FTIR spectroscopy, which shows peaks assigned to Bronstëd acid sites.
Disproportionation of ethylbenzene over SAPO-40
Lourenço, J. P.; Ribeiro, M. F.; Ramôa Ribeiro, F.; Rocha, J.; Gabelica, Z.SAPO-40 exhibits strong acid sites, which catalyse the reaction of disproportionation of ethylbenzene. The distribution of diethylbenzene isomers suggests a high void volume in the structure of this molecular sieve.
Incorporation of cobalt in the AFR structure and characterization of the result...
Lourenço, J. P.; Ribeiro, M. F.; Ribeiro, F. R.; Rocha, J.; Gabelica, Z.; Onida, B.; Garrone, E.The AFR structure with the silicoaluminophosphate composition (SAPO-40) was known since 1984. However the synthesis of AIPO4-40 and MeAPO4-40 (Me:Co, Zn) was only reported in 1994, hence offering new potential applications of this structure.
Síntese e caracterização de silicoaluminofosfatos do tipo SAPO-40
Lourenço, J. P.; Ribeiro, M. F.; Ribeiro, F. R.; Rocha, J.; Gabelica, Z.Os aluminofosfatos e silicoaluminofosfatos constituem duas das novas famílias de sólidos microporosos com estrutura tipo zeolítico. Estes materiais que apresentam elevada estabilidade térmica e hidrotérmica,podem possuir propriedades ácidas importantes, que associadas à sua estrutura de poros, lhes conferem novas e interessantes potencialidades de utilização no domínio da catálise, adsorção e permuta iónica.
Study of catalytic properties of SAPO-40
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 stron...
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