A homogeneous ceria-based mixed-
metal oxide, useful as a
catalyst support, a co-catalyst and / or a
getter, is described. The mixed-
metal oxide has a relatively large surface area per weight, typically exceeding 150 m<2> / g, a structure of nanocrystallites having diameters of less than 4 nm, and including pores larger than the nanocrystallites and having diameters in the range of 4 to about 9 nm. The ratio of the pore volumes, VP, to skeletal structure volumes, VS, is typically less than about 2.5, and the surface area per
unit volume of the
oxide material is greater than 320 m<2> / cm<3>, such that the structural morphology supports both a relatively low internal
mass transfer resistance and large
effective surface area for reaction activity of interest. The
mixed metal oxide is made by co-precipitating a dilute
metal salt solution containing the respective metals, which may include Zr, Hf, and / or other metal constituents in addition to Ce, replacing water in the co-precipitate with a water-miscible low surface-tension
solvent, and relatively quickly
drying and calcining the co-precipitate at moderate temperatures. A highly dispersive catalyst metal, such as Pt, may be loaded on the
mixed metal oxide support from a catalyst-containing solution following a selected acid surface treatment of the oxide support. The
mixed metal oxide, as
catalyst support, co-catalyst or
getter, is applied in various reactions, and particularly
water gas shift and / or preferential oxidation reactions as associated with fuel
processing systems, as for
fuel cells and the like.