| 摘要 |
A doped, nanocrystalline, ceria-containing, mixed metal oxide supports a noble metal to provide a thermally-durable catalyst for processing carbonaceous fuels, particularly for the water gas shift reactions. The mixed metal oxide includes Zr and/or Hf and is normally susceptible to oxide ion vacancy ordering at elevated temperature reducing conditions. A dopant is selected to inhibit such oxide ion vacancy ordering. The dopant is preferably selected from the group consisting of W, Mo, Ta, and Nb, most preferably W, for providing a thermally-durable catalyst at operating temperatures exceeding 400 °C. The noble metal is preferably Pt and/or Re. The doped ceria-containing mixed metal oxide is prepared from 2 or 3 aqueous solutions variously containing ceria, Zr and/or Hf, the dopant, and urea. The solutions are heated to below boiling, combined in a particular sequence and manner, and brought to boiling to crystallize and precipitate the doped ceria-containing mixed metal oxide. |
