Collect. Czech. Chem. Commun. 1994, 59, 1922-1930

TPSR, TPR, and TPO Studies of Pd-V2O5/Al2O3 Catalysts in Complete Catalytic Oxidation of Benzene

Snejana Dancheva, Liuba Ilieva, Nikolay Kotsev and Atanas Andreev

Institute of Kinetics and Catalysis, Bulgarian Academy of Sciences, Sofia 1113, Bulgaria


Alumina-supported palladium vanadium-pentoxide catalysts were studied by means of temperature-programmed surface reaction, temperature-programmed reduction, temperature-programmed oxidation, and by ESR spectroscopy in the complete oxidation of benzene. The surface reaction measurements indicated that 0.5% Pd - 30% V2O5 / Al2O3 produced most oxidation products, compared to 0.5% Pd / Al2O3 or 30% V2O5 / Al2O3 samples. A drastic fall of peak maxima in temperature-programmed oxidation and reduction spectra indicates the decisive role of palladium in the mixed metal metal oxide system in facilitating the vanadium redox transitions. During initial period of catalysts operation, there proceeds formation of vanadium oxide phases which contain clustered V4+ ions in a matrix of vanadium pentoxide. These ions are responsible for the high activity of the palladium vanadium pentoxide catalyst.