The dehydration and rehydration of a catalytically active (superacid) sulfate-doped ZrOz system has been studied by IR spectroscopy. By the adsorption of pyridine, the acidity of the system has been tested in various stages of the dehydration/rehydration process. Bronsted acid centers are abundantly present and are in different hydration states after dehydration at temperatures in the 300-473 K interval. For dehydration at T > 473 (but not higher than 900 K), declining amounts of acid protonic centers are still present and are in an anhydrous form; the original Bronsted acidity can be regenerated upon rehydration at ambient temperature.
On the Brønsted acidity of a superacid sulfate-doped ZrO2 system
MORTERRA, Claudio;CERRATO, Giuseppina;
1994-01-01
Abstract
The dehydration and rehydration of a catalytically active (superacid) sulfate-doped ZrOz system has been studied by IR spectroscopy. By the adsorption of pyridine, the acidity of the system has been tested in various stages of the dehydration/rehydration process. Bronsted acid centers are abundantly present and are in different hydration states after dehydration at temperatures in the 300-473 K interval. For dehydration at T > 473 (but not higher than 900 K), declining amounts of acid protonic centers are still present and are in an anhydrous form; the original Bronsted acidity can be regenerated upon rehydration at ambient temperature.
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