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US 2006/0233691 A1Published application
Durable catalyst for processing carbonaceous fuel, and the method of making
OwnerThomas Vanderspurt, Rhonda Williganinventors
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OwnerThomas Vanderspurt, Rhonda Williganinventors
Estimating the term…
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.
A homogeneous, nanocrystalline, mixed metal oxide of cerium and at least a first other metal constituent selected from a first group consisting of Zr and Hf and normally being susceptible to oxide ion vacancy ordering for temperatures greater than about 320° C. and further including at least a second other metal constituent selected as a dopant to inhibit oxide ion vacancy ordering, said mixed metal oxide having an average crystallite size less than 6 nm and agglomerated to form a skeletal structure with pores, average pore diameters being in the range between about 4 nm and 9 nm and normally being greater than the average crystallite size, and wherein the surface area of the skeletal structure per volume of the material of the structure is greater than about 240 m2/cm3.
In a water gas shift reactor having the reformate of a carbonaceous fuel flowed in reactive contact with a catalyst for providing a water gas shift reaction, the catalyst comprising a noble metal supported on a homogeneous, nanocrystalline, mixed metal oxide, the mixed metal oxide comprising cerium and at least a first other metal constituent selected from a first group consisting of Zr and Hf and normally being susceptible to oxide ion vacancy ordering and further including at least a second other metal constituent selected to inhibit oxide ion vacancy ordering, said mixed metal oxide having an average crystallite size less than 6 nm and agglomerated to form a skeletal structure with pores, average pore diameters being in the range of about 4 nm to 9 nm and normally being greater than the average crystallite size, and wherein the surface area of the skeletal structure per volume of the material of the structure is greater than about 240 m2/cm3.
Dependencies are inferred from the claim text.