REACTION OF BENZENE AND PYRIDINE ON METAL-PROMOTED SULFATED ZIRCONIA CATALYSTS

The reactions of benzene and pyridine on sulfated zirconia (I), O.6 wt %Pt/SO42-/ZrO2 (II), and 2 wt% Fe/0.5 wt% Mn/SO42-/ZrO2 (III) upon hea ting between 100 and 800 degrees C in an inert atmosphere were studied with a TG/MS instrument. Benzene was converted to carbon dioxide and coke, whereas most pyridine reacted in the same way, but a minor amoun t was desorbed unchanged. Sulfur dioxide and oxygen also evolved in al l cases. Formation of sulfur dioxide indicates that sulfate is the oxi dizing species. The coke was also converted to CO2 in a second heating cycle, conducted in air, but the solid gained weight in this step, in dicating that some of the oxygen consumed for the oxidation of the org anic molecules originated in the ZrO2. These results show that the TPD of very weak (benzene) or even stronger (pyridine) organic bases does not measure the acidity of sulfated zirconia or of composite material s based on it. (C) 1996 Academic Press, Inc.