Pt-TiO2-γ Al2O3 catalyst -: I.: Dispersion of platinum on alumina-grafted titanium oxide

Polymeric titanium oxides grafted on gamma-Al2O3 were used as supports for platinum catalysts containing 1 wt.% Pt. The supports were prepared from an interaction of alumina with titanium isopropoxide, impregnated with hexachloroplatinum acid (H2PtCl6) and calcined at 773 K, Pure alumina and titania were used for comparison. The solids were characterized by XRD, TPR, DRS-UV-vis, and TEM. Frontal hydrogen chemisorption was measured after TPR, CO adsorption isotherms were recorded after reduction at low (573 K) and high (773 K) temperature. The results indicate that the polymeric titanium oxide layer in the catalyst, although reducible under hydrogen at high temperature, does not promote a strong metal-support interaction effect. Platinum dispersions in the titania-modified catalysts are higher than in alumina catalysts. (C) 1999 Academic Press.