Artículo
Wells–Dawson heteropolyacid supported on silica: isobutane alkylation with C4 olefins
Fecha de publicación:
09/2001
Editorial:
Elsevier Science
Revista:
Applied Catalysis A: General
ISSN:
0926-860X
Idioma:
Inglés
Tipo de recurso:
Artículo publicado
Clasificación temática:
Resumen
The alkylation of isobutane with C4 olefins is studied, using heteropolyacids (HPA) with Wells–Dawson (WD) structure supported on silica (WD/SiO2). The catalytic performance of these catalysts is compared with a lanthanum-exchanged Y-zeolite catalyst. The loading of the HPA on silica was varied between 9 and 28 wt.%. These catalysts have activity for trimethylpentanes (TMP) production. The selectivity towards these products is not as high as in the case of the lanthanum containing Y-zeolite. The acidity of WD/SiO2 catalysts increases as the loading increases, as seen by MAS-NMR. Correspondingly, a better TMP production is observed. The increase both in acidity and in the TMP production as a function of the WD content is more noticeable at low loading. The coke formed during the reaction requires high temperatures, 550°C approximately, in order to be fully removed with an oxygen containing carrier gas. The temperature-programmed oxidation (TPO) profile of this coke displays two peaks, the first one between 80 and 300°C associated with hydrocarbons that are released upon heating, and the second between 300 and 550°C, associated with coke that changed its structure during the heating. A regeneration at intermediate temperatures, e.g. 300°C, removes the coke that corresponds to the first peak, but does not restore the initial activity. If the regeneration is carried out at higher temperatures, e.g. 500°C, most of the coke is removed, but this treatment leads to changes in the structure of the HPA, as indicated by FTIR and MAS-NMR analysis. Regeneration with O3 at low temperature (125°C) is effective both for coke removal and to recover the catalytic activity.
Palabras clave:
Isobutane Alkylation
,
Heteropolyacids
,
Wells-Dawson
,
Regeneration
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Articulos(CINDECA)
Articulos de CENTRO DE INV EN CS.APLICADAS "DR.JORGE J.RONCO"
Articulos de CENTRO DE INV EN CS.APLICADAS "DR.JORGE J.RONCO"
Articulos(INCAPE)
Articulos de INST.DE INVEST.EN CATALISIS Y PETROQUIMICA "ING. JOSE MIGUEL PARERA"
Articulos de INST.DE INVEST.EN CATALISIS Y PETROQUIMICA "ING. JOSE MIGUEL PARERA"
Citación
Baronetti, Graciela Teresita; Thomas, Horacio Jorge; Querini, Carlos Alberto; Wells–Dawson heteropolyacid supported on silica: isobutane alkylation with C4 olefins; Elsevier Science; Applied Catalysis A: General; 217; 1-2; 9-2001; 131-141
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