Characterization of the metallic phase in nanocrystalline ZnAl2O4-supported Pt catalysts

In this study several complementary methods as XRD, HRTEM, O₂ and H₂ adsorption, as well as H₂-O₂ titration were used for characterization of the metallic phase in 0.5-3.0 wt.% Pt/ZnAl₂O₄ catalysts. Three nanocrystalline ZnAl₂O₄ spinels used as a supports were prepared by the solvothermal and co-precipitation method. It was found that irrespective of the preparation method they form very good support materials with a high capacity to achieve high platinum dispersion. O₂ and H₂ chemisorption data showed metal dispersion up to 90% and good correspondence with HRTEM results was observed. The H₂-O₂ titration method may be applied for determination of Pt dispersion only in the high-loaded Pt/ZnAl₂O₄ catalysts. The catalytic performances of Pt supported on the prepared spinels were evaluated in the propane total oxidation reaction.