An apparatus and a method for continuous solvothermal synthesis of nanoparticles, are provided. The apparatus includes an inlet section, a reactor section, a flexible quenching unit, and an outlet section. The inlet section separately receives reactants including the solvent and a precursor solution that are allowed to flow into the reactor section. The reactor section includes multiple spiral turns such that each of the spiral turns includes a helical channel followed by a counter-helical channel for enabling mixing of the reactants to cause solvothermal reactions between them. The counter-helical channel changes the direction of flow of reactants upon flow of said reactants from the helical channel to the counter-helical channel. The flexible quenching section enclosing a portion of the reactor section quenches a slurry formed as a result of the solvothermal reactions, wherein the slurry includes the nanoparticles of targeted characteristics. The outlet section facilitates withdrawal of the slurry.

An apparatus and a method for continuous solvothermal synthesis of nanoparticles, are provided. The apparatus includes an inlet section, a reactor section, a flexible quenching unit, and an outlet section. The inlet section separately receives reactants including the solvent and a precursor solution that are allowed to flow into the reactor section. The reactor section includes multiple spiral turns such that each of the spiral turns includes a helical channel followed by a counter-helical channel for enabling mixing of the reactants to cause solvothermal reactions between them. The counter-helical channel changes the direction of flow of reactants upon flow of said reactants from the helical channel to the counter-helical channel. The flexible quenching section enclosing a portion of the reactor section quenches a slurry formed as a result of the solvothermal reactions, wherein the slurry includes the nanoparticles of targeted characteristics. The outlet section facilitates withdrawal of the slurry.

The present invention relates to cerium oxide particles that have excellent heat resistance especially useful for catalysts, functional ceramics, solid electrolyte for fuel cells, polishing, ultraviolet absorbers and the like, and particularly suitable for use as a catalyst or co-catalyst material, for instance in catalysis for purifying vehicle exhaust gas. The present invention also relates to a method for preparing such cerium oxide particles, and a catalyst, such as for purifying exhaust gas, utilizing these cerium oxide particles.

The present invention relates to cerium oxide particles that have excellent heat resistance especially useful for catalysts, functional ceramics, solid electrolyte for fuel cells, polishing, ultraviolet absorbers and the like, and particularly suitable for use as a catalyst or co-catalyst material, for instance in catalysis for purifying vehicle exhaust gas. The present invention also relates to a method for preparing such cerium oxide particles, and a catalyst, such as for purifying exhaust gas, utilizing these cerium oxide particles.

With an aim to provide an oxide particle with controlled color characteristics, the present invention provides a method for producing an oxide particle, wherein the color characteristics of the oxide particle are controlled by controlling a M-OH bond/M-O bond ratio, which is a ratio of a M-OH bond between an element (M) and a hydroxide group (OH) to a ratio of an M-O bond between the element (M) and oxygen (O), where the element (M) is one or plural different elements other than oxygen or hydrogen included in the oxide particle selected from metal oxide particles and semi-metal oxide particles. According to the present invention, by controlling the M-OH bond/M-O bond ratio of the metal oxide particle or the semi-metal oxide particle, the oxide particle with controlled color characteristics of any of reflectance, transmittance, molar absorption coefficient, hue, and saturation can be provided.

A slurry containing abrasive grains and a liquid medium, in which the abrasive grains include first particles and second particles in contact with the first particles, the first particles contain cerium oxide, the second particles contain a cerium compound, and an Rsp value calculated by Formula (1) below is 1.60 or more:

Rsp=(Tb/Tav)−1  (1)

[in the formula, Tav represents a relaxation time (unit: ms) obtained by pulsed NMR measurement of the slurry in a case where a content of the abrasive grains is 2.0% by mass, and Tb represents a relaxation time (unit: ms) obtained by pulsed NMR measurement of a supernatant solution obtained when the slurry is subjected to centrifugal separation for 50 minutes at a centrifugal acceleration of 2.36×10.sup.5 G in a case where the content of the abrasive grains is 2.0% by mass.]

A slurry containing abrasive grains and a liquid medium, in which the abrasive grains include first particles and second particles in contact with the first particles, a particle size of the second particles is smaller than a particle size of the first particles, the first particles contain cerium oxide, the second particles contain a cerium compound, and in a case where a content of the abrasive grains is 0.1% by mass, a BET specific surface area of a solid phase obtained when the slurry is subjected to centrifugal separation for 60 minutes at a centrifugal acceleration of 1.1×10.sup.4 G is 40 m.sup.2/g or more.

The present invention relates to silicon-compound-coated fine metal particles, with which surfaces of fine metal particles, composed of at least one type of metal element or metalloid element, are at least partially coated with a silicon compound and a ratio of Si—OH bonds contained in the silicon-compound-coated fine metal particles is controlled to be 0.1% or more and 70% or less. By the present invention, silicon-compound-coated fine metal particles that are controlled in dispersibility and other properties can be provided by controlling the ratio of Si—OH bonds or the ratio of Si—OH bonds/Si—O bonds contained in the silicon-compound-coated fine metal particles. By controlling the ratio of Si—OH bonds or the ratio of Si—OH bonds/Si—O bonds, a composition that is more appropriate for diversifying applications and targeted properties of silicon-compound-coated fine metal particles than was conventionally possible can be designed easily.

A method for the precipitation of rare earth sulphate, the method including subjecting a crude rare earth sulphate solution to precipitation in the presence of a water soluble, volatile, organic compound to produce a rare earth sulphate precipitate and an acidic supernatant. The organic compound is preferably selected from the group consisting of methanol, ethanol, iso-propanol, tert-butanol, acetone or mixtures thereof, and is preferably methanol. Preferably, the organic compound is used in the precipitation at a weight ratio of between 0.25:1 to 1.5:1, and preferably 0.5:to 1.25:1, with the crude sulphate solution.

A method of processing a purified rare earth sulphate solution, the method including the steps of: contacting the purified rare earth sulphate solution with sodium hydroxide to precipitate rare earths as rare earth hydroxide, including the addition of an oxidant to oxidise cerium contained in the rare earth hydroxide precipitate; and selectively leaching the rare earth hydroxide precipitate with hydrochloric acid to form a rare earth chloride solution and a residue.