BRONSTED ACIDITY OF A SUPERACID SULFATE-DOPED ZRO2 SYSTEM

The dehydration and rehydration of a catalytically active (superacid) sulfate-doped ZrO2 system has been studied by IR spectroscopy. By the adsorption of pyridine, the acidity of the system has been tested in v arious stages of the dehydration/rehydration process. Bronsted acid ce nters are abundantly present and are in different hydration states aft er dehydration at temperatures in the 300-473 K interval. For dehydrat ion at T greater than or equal to 473 (but not higher than approximate to 900 K), declining amounts of acid protonic centers are still prese nt and are in an anhydrous form; the original Bronsted acidity can be regenerated upon rehydration at ambient temperature.