http://www.cnr.it/ontology/cnr/individuo/prodotto/ID33628
Wox/zro2 catalysts. Part 2. Isomerization of n-butane. (Articolo in rivista)
- Type
- Label
- Wox/zro2 catalysts. Part 2. Isomerization of n-butane. (Articolo in rivista) (literal)
- Anno
- 2002-01-01T00:00:00+01:00 (literal)
- Alternative label
De Rossi S., Ferraris G., Valigi M., Gazzoli D. (2002)
Wox/zro2 catalysts. Part 2. Isomerization of n-butane.
(literal)
- Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori
- De Rossi S., Ferraris G., Valigi M., Gazzoli D. (literal)
- Pagina inizio
- Pagina fine
- Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#numeroVolume
- Note
- ISI Web of Science (WOS) (literal)
- Titolo
- Wox/zro2 catalysts. Part 2. Isomerization of n-butane. (literal)
- Abstract
- The activity of WOx/ZrO2 (ZW) catalysts for n-butane isomerization was
investigated in the temperature range 423-673 K. Reference samples of
crystalline WO3 and ZrO2 displayed low catalytic activity. When ZW
catalysts were calcined at 873 or 1073 K, samples prepared from amorphous
hydrous zirconia showed activity levels - both on areal rate and turnover
frequency per total tungsten bases - that were 1 order of magnitude higher
than those of the samples prepared from crystalline zirconia. The higher
the calcination temperature in the range 873-1073 K the higher was the
activity. The deactivation due to coking was fast, but treatment with
flowing oxygen at 773 K completely restored the catalytic activity for
several cycles. The activity decrease with time on stream was
satisfactorily described up to 623 K by the empirical equation r=at^-n.
Active isomerization sites in the catalysts produced coke (average
composition H/C=1.5). The presence of hydrogen in the reactant stream
substantially decreased the deactivation rate, most probably by hindering
the dehydrogenation reactions which ultimately lead to coke formation.
Treating catalysts in hydrogen at 673 or at 443 K before the reaction
shortened the induction period, suggesting that hydrogen adsorption had a
role in generating hydroxyls active for the isomerization (Bronsted acid
sites). The activity trend with surface density of tungsten indicated a
polynuclear isomerization site. (literal)
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