With an aim to provide a method for producing an oxide particle with controlled color characteristics and also 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 ratio of an M-OH bond between an element (M) and a hydroxide group (OH) or an M-OH bond/M-O bond ratio, where the element (M) is one element 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 or 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.

An iron powder and method of making an iron powder. The method includes a step of neutralizing an acidic aqueous solution containing a trivalent iron ion and a phosphorus-containing ion, with an alkali aqueous solution, so as to provide a slurry of a precipitate of a hydrated oxide, or a step of adding a phosphorus-containing ion to a slurry containing a precipitate of a hydrated oxide obtained by neutralizing an acidic aqueous solution containing a trivalent iron ion with an alkali aqueous solution. A silane compound is added to the slurry so as to coat a hydrolysate of the silane compound on the precipitate of the hydrated oxide. The precipitate of the hydrated oxide after coating is recovered through solid-liquid separation, the recovered precipitate is heated to provide iron particles coated with a silicon oxide, and a part or the whole of the silicon oxide coating is dissolved and removed.

An iron powder and method of making an iron powder. The method includes a step of neutralizing an acidic aqueous solution containing a trivalent iron ion and a phosphorus-containing ion, with an alkali aqueous solution, so as to provide a slurry of a precipitate of a hydrated oxide, or a step of adding a phosphorus-containing ion to a slurry containing a precipitate of a hydrated oxide obtained by neutralizing an acidic aqueous solution containing a trivalent iron ion with an alkali aqueous solution. A silane compound is added to the slurry so as to coat a hydrolysate of the silane compound on the precipitate of the hydrated oxide. The precipitate of the hydrated oxide after coating is recovered through solid-liquid separation, the recovered precipitate is heated to provide iron particles coated with a silicon oxide, and a part or the whole of the silicon oxide coating is dissolved and removed.

The present invention relates to an improved process for producing iron oxide red pigments by the Penniman process using nitrate (also referred to as nitrate process or direct red process).

The present invention relates to an improved process for producing iron oxide red pigments by the Penniman process using nitrate (also referred to as nitrate process or direct red process).

A method for the processing of potassium containing materials comprises: (i) Separation of a potassium containing mineral from gangue minerals; (ii) Acid leaching whereby substantially all potassium, iron, aluminium and magnesium is solubilised and mixed potassium/iron double salt formed; (iii) Selectively crystallising the mixed potassium/iron double salt formed in the leach step (ii); (iv) Second separation to separate the mixed potassium/iron double salt formed in step (iii); (v) Thermal decomposition to produce an iron oxide, a potassium salt and one or more phosphates; (vi) Leaching the product of the thermal decomposition; (vii) Third separation to separate the iron oxide and phosphate from the potassium salt; (viii) Recovering the potassium salt by crystallisation; (ix) Separating the iron oxide and phosphate of step (vii) by leaching and subsequent solid liquid separation; and (x) Precipitating phosphate from liquor produced in step (ix) through the addition of a base.

A method of preparing a catalyst for oxidative dehydrogenation that includes coprecipitation and injecting inert gas or air at a specific time point to reduce the ratio of an inactive α-Fe.sub.2O.sub.3 crystal structure, thereby improving the activity of the catalyst. Also provided is a method of performing oxidative dehydrogenation using the catalyst. When oxidative dehydrogenation of butene is performed using the catalyst, side reaction may be reduced, and selectivity for butadiene may be improved, providing butadiene with high productivity.

A method of preparing a catalyst for oxidative dehydrogenation that includes coprecipitation and injecting inert gas or air at a specific time point to reduce the ratio of an inactive α-Fe.sub.2O.sub.3 crystal structure, thereby improving the activity of the catalyst. Also provided is a method of performing oxidative dehydrogenation using the catalyst. When oxidative dehydrogenation of butene is performed using the catalyst, side reaction may be reduced, and selectivity for butadiene may be improved, providing butadiene with high productivity.

The present invention disclosed use of lactam as a solvent in the preparation of nanomaterials by precipitation method, sol-gel method or high temperature pyrolysis. These methods are able to recycle lactam solvent, which meet requirements of environmental protection.

The present invention disclosed use of lactam as a solvent in the preparation of nanomaterials by precipitation method, sol-gel method or high temperature pyrolysis. These methods are able to recycle lactam solvent, which meet requirements of environmental protection.