Abstract Claims Description Full Text

Abstract

Perovskite-type catalyst consists essentially of a metal oxide composition and methods of using them are provided. The metal oxide composition is represented by the general formula Aa−xBxMOb, in which A is a mixture of elements originally in the form of single phase mixed lanthanides collected from bastnasite; B is a divalent or monovalent cation; M is at least one element selected from the group consisting of elements of an atomic number of from 23 to 30, 40 to 51, and 73 to 80; a is 1 or 2; b is 3 when a is 1 or b is 4 when a is 2; and x is a number defined by 0≦x<0.5. Methods of making and using the perovskite-type catalysts are also provided. The perovskite-type catalyst may be used to reduce nitrogen oxides, oxidize carbon monoxide, and oxidize hydrocarbons in an exhaust stream from a motor vehicle. Methods of such a use are provided.

Other References

• Marcilly et al., Preparation of Highly Dispersed Mixed Oxides and Oxide Solid Solutions by Pyrolysis of Amorphous Organ Precursors, J. Am. Ceram. Soc., 53 (1970) 560, no month.
• Libby, Promising Catalyst for Auto Exhaust, Science, 171 (1971) 499, no month.
• Voorhoeve et al., Rare-Earth Oxides of Manganese and Cobalt Rival Platinum for the Treatment of Carbon Monoxide in Auto Exhaust, Science, 177 (Jul., 1972) 353.
• Voorhoeve et al., Rare-Earth Manganites: Catalysts with Low Ammonia Yield in the Reduction of Nitrogen Oxides, Science 180 (Apr., 1973).
• Voorhoeve et al., Perovskite Oxides: Materials Science in Catalysis, Science, 195 (Mar., 1977) 827.
• Voorhoeve et al., Exploration of Persovskite-Like Catalysts, Mat. Res. Bull., 9 (1974) 655, no month.
• Johnson et al., Preparation of High Surface Area Substituted LaMnO₃ Catalysts, Ceramic Bulletin, 55 (1976) 520, no month.
• Baythoun et al., Production of strontium-substituted lanthanum manganite perovskite powder by the amorphous citrate process, J. Mat. Sci., 17 (1982) 2757, no month.
• Asamitsu, A structural phase transition induced by an external magnetic field, Nature, 373 (Feb., 1995) 407.
• Chakraborty et al., Low-temperature systhesis of ultrafine La0.84 MnO₃ powder by an autoignition process, J. Mat. Res., 9 (1994) 986, no month.
• Kilbourn, B.T., Lanthanides and Yttrium (Raw Materials for Advanced and Engineered Ceramics), Cer. Eng. Sc. Proc. By, _—(1985) pp. 1331-1341, no month.
• Habashi, F., The Discovery and Industrialization of the Rare Earths, UNOCAL⁷⁶MOLYCORP, (1994), reprinted from CIM Bulletin Jan. and Feb., 1994.
• Sakaguchi et al, Electrocatalytic Activity and Oxygen Adsorption Property of Perovskite-type Oxides, Electrochimica Acta, 35 (1990) 65, no month.
• Meadowcroft, D.B., Low-cost Oxygen Electrode Material, Nature, 226 (1970) 847, no month.
• Johnson et al., Studies of some Perovskite Oxidation Catalysts Using DTA Techniques, Thermochimica Acta,7 (1973) 303, no month.
• Tseung et al, Preparation and Characterization of High Surface Area Semiconducting Oxides, J. Mater. Sci., 5 (1970) 604, no month.
• Ni, Yunxiang et al, The atomic arrangement of bastnasite-(Ce), Ce (CO3)F, and structural elements of synchysite-(Ce), rontgenite-(Ce), and parisite-(Ce), Am. Mineral., 78 (1993) 415, no month.
• M. Fleischer, Relative Proportions of the Lanthanides in Minerals of the Bastnaesite Group, Can. Mineral, 16 (1978) 361, no month.
• Ohbayashi et al., Crystallographic, Electric and Thermochemical Properties of the Perovskite-Type Ln_1-xSr_xCoO₃(Ln: Lanthanoid Element), Japanese Journal of Applied Physics, vol. 13, No..1, Jan. 1974, 1-7.
• Taylor, Automobile Catalytic Converters, Springer-Verlag., 1984, pp. 4, 5, 11, no month.
• Heck and Farrauto, Automobile Catalysts, Automotive Engineering, Feb. 1996, 93-96.
• Narula et al., Materials Chemistry Issues Related to Advanced Materials Applications in the Automotive Industry, Chem. Mater, vol. 8, No. 5, 1996, 984-1003, no month.
• Voorhoeve et al., Defect Chemistry and Catalysis in Oxidation and Reduction Over Perovskite-Type Oxides, Annals New York Academy of Science, 1976, pp. 3-21, no month.
• Viswanathan, CO Oxidation and NO Reduction on Perovskite Oxides, Catal. Rev.-Sci. Eng., 34(4), 337-354 (1992), no month.
• Burton & Garten, Advanced Materials in Catalysis, Academic Press, New York, 1997, no month.
• Nakamura et al., Reduction-Oxidation and Catalytic Properties of La_1-xSr_xCoO₃, Journal of Catalysis, 83, 151-159 (1983), no month.
• Nitadori & Misono, Catalytic Properties of La_1-x, A′_xFeO₃ (A′ = Sr₁ Ce) and La_1-xCe_xCoO₃ , Journal of Catalysis, 93, 459-466 (1985), no month.
• Nitadori et al., Catalytic Properties of La_1-x, A'xMnO₃ (A' = Sr₁ Ce, Hf), Journal of Catalysis, 98, 221-228 (1986), no month.
• Kirk-Othmer, Encyclopedia of Chemical Technology, 3ed., vol. 19, 833-838 (1982), no month.