A hydrothermal method of preparing uniform, monodisperse ceramic lanthanum hydroxyl carbonate (LaCO.sub.3OH) having cherry-blossom-like nanogears and/or nanocubes is described. The method produced a hexagonal crystal with a crystal lattice in which at least on lanthanum ion is substituted with calcium ion. The ceramic nanoparticles produced by the method are good catalyst for the reduction of nitrogen oxides with a hydrocarbon. A method of reducing exhaust gases is described.

To provide a molded article which can have excellent strength, can also have high durability during repeated use, and can maintain high adsorption performance even when the content of a binder resin is reduced. A molded article containing cerium oxide particles and a binder resin, wherein cerium oxide particles which has an average particle diameter of 1 to 15 m and in each of which a crystallite size is 40 to 200 are used.

Provided is a method for electrowinning neodymium compound. The method includes providing a fluoride-based electrolyte through an opening defined in an electrolytic bath including a cathode and an anode. The method includes providing granules, each including a neodymium compound and having at least one cavity defined therein, through the opening defined in the electrolytic bath. The method includes dissolving at least a portion of the granule in a molten salt of the fluoride-based electrolyte. The method also includes reducing neodymium at the cathode. The cavity is defined inside or on the surface of the granule, and the apparent density of the granules is lower than the density of the molten salt. The method proposed has an improved process compared to those of the related art.

A slurry of a dispersion medium and rare earth oxide particles. The particles having a volume basis median particle size D50 of up to 50 nm. The rare earth oxide particles having a dispersity index S of up to 1, the dispersity index S being determined according to the formula (1):
(D90D10)/D50(1) wherein D10, D50 and D90 are cumulative 10%, 50% and 90% diameters in volume basis particle size distribution, respectively.

A hydrothermal method of preparing uniform, monodisperse ceramic lanthanum hydroxyl carbonate (LaCO.sub.3OH) having cherry-blossom-like nanogears and/or nanocubes is described. The method produced a hexagonal crystal with a crystal lattice in which at least on lanthanum ion is substituted with calcium ion. The ceramic nanoparticles produced by the method are good catalyst for the reduction of nitrogen oxides with a hydrocarbon. A method of reducing exhaust gases is described.

A hydrothermal method of preparing uniform, monodisperse ceramic lanthanum hydroxyl carbonate (LaCO.sub.3OH) having cherry-blossom-like nanogears and/or nanocubes is described. The method produced a hexagonal crystal with a crystal lattice in which at least on lanthanum ion is substituted with calcium ion. The ceramic nanoparticles produced by the method are good catalyst for the reduction of nitrogen oxides with a hydrocarbon. A method of reducing exhaust gases is described.

Mixed rare earth carbonate may be prepared by mixing a rare earth double sulfate salt solid with a conversion agent comprising a sodium carbonate (Na.sub.2CO.sub.3) solution, to form a slurry mixture, and generating a low sulfate rare earth carbonate wet cake from the slurry mixture.

Mixed rare earth carbonate may be prepared by mixing a rare earth double sulfate salt solid with a conversion agent comprising a sodium carbonate (Na.sub.2CO.sub.3) solution, to form a slurry mixture, and generating a low sulfate rare earth carbonate wet cake from the slurry mixture.

A hydrothermal method of preparing uniform, monodisperse ceramic lanthanum hydroxyl carbonate (LaCO.sub.3OH) having cherry-blossom-like nanogears and/or nanocubes is described. The method produced a hexagonal crystal with a crystal lattice in which at least on lanthanum ion is substituted with calcium ion. The ceramic nanoparticles produced by the method are good catalyst for the reduction of nitrogen oxides with a hydrocarbon. A method of reducing exhaust gases is described.

A phosphorus adsorbent, which is used for adsorbing phosphorus in extracorporeal circulation, is a powder comprising a carbonate of a rare earth metal or an oxide of a Group 4 element and having a solubility in 100 g of water at 20 C. of 10 mg or less. The porous fiber, which comprises the phosphorus adsorbent carried therein, shows a change in pH value of from 1.0 to +1.0 inclusive before and after stirring in physiological saline for 4 hours. The phosphorus adsorption columns respectively comprise the phosphorus adsorbent and the porous fiber each disposed therein.