Thermal stability, acidity, catalytic properties, and deactivation behaviour of SAPO-5 catalysts: Effect of silicon content, acid treatment, and Na exchange

Journal Article · Thu Sep 01 04:00:00 EDT 1994 · Journal of Catalysis

DOI:https://doi.org/10.1006/jcat.1994.1267· OSTI ID:110972

Akolekar, D B ^[1]

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1. Univ. of New South Wales, Kensington (Australia)

Crystalline microporous SAPO-5 molecular sieves with different silicon content, acid-treated SAPO-5 and Na-exchanged SAPO-5 were investigated for their thermal stability, and acidic and catalytic properties. SAPO-5 materials with increasing SI framework content exhibited lower thermal stability. The effects of the thermal treatment and Na exchange on the N{sub 2}-sorption capacity (at 78 K) of these materials were studied. In situ IR spectroscopic investigations of pyridine chemisorbed on the aluminophosphate catalysts revealed that the concentration of Broensted and Lewis acid sites are strongly affected by the Si content in the AlPO{sub 4} framework, acid treatment, and Na exchange. The results of temperature programmed desorption (TPD) and stepwise thermal desorption of pyridine suggest that there exists a broad site energy distribution over the aluminophosphate catalysts increases with the increasing Si content in the AlPO{sub 4} framework. The acid treatment and Na exchange showed a decrease in the number of strong acid sites on SAPO-5. The TPD of pyridine over SAPO-5, acid-treated SAPO-5, and Na-exchanged SAPO-5 indicated the presence of two types of acid sites. Correlation between the number of strong acid sites (measured in terms of the chemisorption of pyridine at 673 K) and framework charge on the aluminophosphate catalysts has also been obtained. The catalytic activities of SAPO-5 catalysts in the ethanol, n-hexane, isooctane, toluene, and o-xylene conversion reactions were studied. 22 refs., 11 figs., 5 tabs.

• OSTI ID: 110972
• Journal Information: Journal of Catalysis, Journal Name: Journal of Catalysis Journal Issue: 1 Vol. 149; ISSN 0021-9517; ISSN JCTLA5
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
40 CHEMISTRY
ABSORPTION SPECTROSCOPY
ALKANES
CATALYTIC EFFECTS
CHEMICAL PREPARATION
ETHANOL
HEXANE
MOLECULAR SIEVES
PYRIDINE
SORPTIVE PROPERTIES
STABILITY
TEMPERATURE DEPENDENCE
TOLUENE
XYLENES