Pt-TiO2-gamma 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 hexach loroplatinum acid (H2PtCl6) and calcined at 773 K, Pure alumina and titania were used for comparison. The solids were characterized by XRD, TPR, DRS-U V-vis, and TEM. Frontal hydrogen chemisorption was measured after TPR, CO a dsorption 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 temperatur e, does not promote a strong metal-support interaction effect. Platinum dis persions in the titania-modified catalysts are higher than in alumina catal ysts. (C) 1999 Academic Press.