Abstract

Zinc aluminate was synthesized by coprecipitation and after calcination at 8000 C was impregnated with chloroplatinic acid to obtain 0.16,0.47,1.17 and 2.5 weight percentage of platinum catalysts. Samples were characterized by atomic absorption, nitrogen physisorption, X-ray diffraction, hydrogen chemisorption, conventional and high-resolution electron microscopy (CTEM y HREM respectively), and catalytic activity in isobutane dehydrogenation. Zinc aluminate showed a high crystallinity (spinel structure) and low surface area - 0.20 m/g. The highest dispersion (49%) was obtained with the 0.16% Pt catalyst diminishing sharply with the other platinum content catalysts. At low Pt concentrations (0.16 - 0.47), it was not possible to localize and distinguish metal particles in HREM images. With the 1.17 % and 2.25 % Pt, samples with clear Pt aggregates with sizes around 2.0 nm could be seen. The catalytical activity was more sensitive to metallic content than to platinum dispersion.