HYDROGEN SPILLOVER PHENOMENA ON PT ZRO2

A Pt/ZrO2 catalyst has been investigated by temperature-programmed red uction and temperature-programmed desorption of hydrogen. Hydrogen spi lls over from Pt onto the ZrO2 surface at about 550 degrees C. One par t of spillover hydrogen is consumed by a partial reduction of zirconia . The other part is adsorbed on the surface and is desorbed at about 6 50 degrees C. This desorption is a reversible one, i.e. it can be foll owed by a renewed uptake of spillover hydrogen. No connection between dehydroxylable OH groups and spillover hydrogen adsorption has been ob served. The adsorption sites for the reversibly bound spillover hydrog en were possibly formed during the reducing hydrogen treatment.