INFLUENCE OF THE NATURE OF THE PLATINUM PRECURSOR ON THE SURFACE-PROPERTIES AND CATALYTIC ACTIVITY OF ALUMINA-SUPPORTED CATALYSTS

The influence of the nature of the metal precursor - platinum acetylac etonates and chloroplatinic acid - on the surface proper ties and cata lytic activity of Pt/Al2O3 catalysts is reported. The obtained results indicate that the catalysts prepared by the organometallic route pres ent higher metal dispersion and lower acidity compared with those prep ared from H2PtCl6. On the other hand, XPS results showed that the stat e of platinum is essentially Pt-0 in the catalysts obtained from Pt(ac ac)(2) while in the solids prepared by impregnation of H2PtCl6 there e xists an important contribution of Pt-delta+ species which plays a pos itive role in the hydrogenation of toluene. An additional hydrogen spi llover due to the presence of more acidic support is also suggested as an explanation of the observed catalytic results.