Preparation Of Different Morphology Au/CeO₂ Catalysts And Their Activity For The CO Oxidation

In recent years, many reports show that gold has the catalysis ability of various chemical reactions. Gold catalysts show great research prospects and wide application. Gold droped on nano metal oxide catalyst can purify carbon monoxide gas of environment at room temperature and wet conditions. CeO2 materials have oxygen storage and release function, and it has synergistic effect with the noble metal. Also CeO2 materials can promote the ability of CO oxidation and NOx reduction. This article focuses on the preparation of nanoscale spherical structures cerium oxide materials, then Au was doped on the supports with different morphologies CeO2 to get the Au/CeO2 catalysts. And test were carried out the structure characterization and carbon monoxide catalytic oxidation. So the major work was follow:1. Four different CeO2 sphere nanomaterials (hollow sphere, flowerlike sphere, cube sphere and spherical cluster) were controllably synthesized by carbon sphere template method, hydrothermal and solvothermal method respectively.2. Au (5 wt%) was doped on the supports by the deposition precipitation method and Au/CeO2 catalysts with three different morphologies were obtained.3. Composition, morphology and structure of these catalysts were characterized by the techniques of XRD, XPS, TPR, SEM and TEM, and the activity for CO oxidation of the catalysts was investigated. The activities of the three catalysts differ largely, the flowerlike Au/CeO2 catalyst had the highest activity for CO oxidation and its T100% was 29℃. And T100% of the hollow sphere and clusters spherical structure Au/CeO2 catalysts are 48℃, 69℃respectively. The mechanism for the different activity of the catalysts was investigated. H2-TPR result and XPS result indicated that flowerlike structure is more advantageous to the metal state gold deposits and dispersed, and more relative contents of surface adsorption oxygen. In summary, gold valence, cerium oxide morphology and surface adsorption oxygen are the factors on the CO catalytic oxidation reaction.