Abstract: Disclosed is a process for production of silicon tetrafluoride which can reduce the cost for the silicon tetrafluoride production and can also reduce the quantities of waste products produced in the process. Also disclosed is an apparatus for use for the process. The method comprises the steps of: (a) a high-silica fluorosilicic acid production step in which a raw material (1) containing silicon dioxide is reacted with a mixed solution containing hydrofluoric acid and hydrofluorosilicic acid to yield an aqueous high-silica fluorosilicic acid solution: (c) a silicon tetrafluoride production step in which the aqueous high-silica fluorosilicic acid solution is reacted with sulfuric acid to yield silicon tetrafluoride; and (d) a sulfuric acid production step in which a sulfuric acid fraction containing hydrogen fluoride which is a by-product in the silicon tetrafluoride production step (c) is subjected to steam stripping to yield sulfuric acid.

Abstract: An isotope enrichment method comprising the step of performing the isotope exchange between an aqueous solution containing at least two components each represented by the formula: H2O—H2SiF6·nSiF4 (wherein n?0) and a gas containing SiF4 to enrich a stable Si isotope.

Abstract: A fine treatment agent according to the present invention is a fine treatment agent for the fine treatment of a multilayer film, including a tungsten film and a silicon oxide film comprising at least one from among hydrogen fluoride, nitric acid, ammonium fluoride and ammonium chloride. Thus, a fine treatment agent which makes fine treatment on a multilayer film, including a tungsten film and a silicon oxide film, possible by controlling the etching rate and a fine treatment method using the same can be provided.

Abstract: Provided is a method for purifying a quaternary alkyl ammonium salt enabling the obtainment of a particulate quaternary alkyl ammonium salt having a low water content at a high yield which is suitably used as an electrolyte in an electrolytic solution. The method for the purification of a quaternary alkyl ammonium salt comprises dispersing a quaternary alkyl ammonium salt to be purified into an organic solvent to allow it to form a suspension there. The alkyl groups constituting the quaternary alkyl ammonium salt have 1 to 5 carbon atoms each. The quaternary alkyl ammonium salt to be purified is dispersed into the organic solvent to make a suspension, and then the particles are washed with an alcohol solvent.

Abstract: Disclosed are a carbon nanotube aggregate and a method for forming a carbon nanotube aggregate. An aggregate can be obtained by fluorinating the surfaces of carbon nanotubes. The method for forming a carbon nanotube aggregate is characterized by comprising a step for firing a plurality of fluorinated carbon nanotubes.

Abstract: The object of the invention is to provide tantalum oxide and/or niobium oxide in the form of hollow particles. Disclosed is a method comprising adding hydrazine or an aqueous solution of hydrazine to (1) an aqueous solution of a tantalum compound and/or a niobium compound, to (2) an aqueous solution of fluorotantalic acid and/or fluoroniobic acid, or to (3) a solution obtained by dissolving crystallized fluorotantalic acid and/or crystallized fluoroniobic acid in water, to produce tantalum hydroxide and/or niobium hydroxide, and firing the tantalum hydroxide and/or niobium hydroxide.

Abstract: A method for preparing tantalum oxide and/or niobium oxide, characterized in that it comprises adding a basic aqueous solution to an aqueous solution of tantalum fluoride salt and/or niobium fluoride salt, to form tantalum hydroxide and/or niobium hydroxide, and then firing said tantalum hydroxide and/or niobium hydroxide. The above method allows the preparation of the tantalum oxide and/or niobium oxide in the state of a needle crystal or columnar crystal, not of a spherical crystal or an assemblage form.

Abstract: This invention aims to develop a chitin oligomer composition and/or a chitosan oligomer composition wherein the content of an oligomer from a trimer to a decamer is 60% or more, and to develop a process for preparing the above-mentioned oligomer composition. The object of the invention can be achieved by mixing hydrofluoric acid or hydrohalogenated acid other than hydrofluoric acid and hydrofluoric acid with a chitin-based material and/or a chitosan-based material.

Abstract: An object of the present invention is to provide a method for purifying a highly pure niobium compound and/or tantalum compound, the method enabling the purification of a highly pure niobium compound and tantalum compound in a simplified manner at a low cost. The object is met by providing a method comprising adding an organic solvent to an aqueous solution containing a niobium compound and/or tantalum compound together with impurities, and then performing extraction via the solution. A niobium compound and/or tantalum compound dissolved in a solution is allowed to precipitate, and said aqueous solution is obtained by dissolving the precipitate in water.

Abstract: The present invention provides a method enabling the high purification of a niobium compound and/or tantalum compound in a simplified manner at a low cost. This is accomplished by providing a method enabling the high purification of a niobium compound and/or tantalum compound comprising the steps of preparing a solution containing niobium and/or tantalum, allowing a precipitate comprising niobium and/or tantalum to develop, separating the precipitate by filtration from the filtrate, converting the precipitate to a liquid melt or taking the filtrate, and separating a niobium compound from a tantalum compound or vice versa by utilizing the difference in solubility to the solvent between the niobium compound and the tantalum compound.

Abstract: Provided is a method for purifying a quaternary alkyl ammonium salt enabling the obtainment of a particulate quaternary alkyl ammonium salt having a low water content at a high yield which is suitably used as an electrolyte in an electrolytic solution. The method for the purification of a quaternary alkyl ammonium salt comprises dispersing a quaternary alkyl ammonium salt to be purified into an organic solvent to allow it to form a suspension there. The alkyl groups constituting the quaternary alkyl ammonium salt have 1 to 5 carbon atoms each. The quaternary alkyl ammonium salt to be purified is dispersed into the organic solvent to make a suspension, and then the particles are washed with an alcohol solvent.

Abstract: The present invention provides a method enabling the high purification of a niobium compound and/or tantalum compound in a simplified manner at a low cost. This is accomplished by providing a method enabling the high purification of a niobium compound and/or tantalum compound comprising the steps of preparing a solution containing niobium and/or tantalum, allowing a precipitate comprising niobium and/or tantalum to develop, separating the precipitate by filtration from the filtrate, converting the precipitate to a liquid melt or taking the filtrate, and separating a niobium compound from a tantalum compound or vice versa by utilizing the difference in solubility to the solvent between the niobium compound and the tantalum compound.

Abstract: In order to provide a method for producing lithium hexafluorophosphate capable of producing lithium hexafluorophosphate of a higher purity than in the related art without the necessity for after-treatment for removal of impurities, a method is characterized by filtering lithium hexafluorophosphate coexisting with a solvent and then carrying out after-filtering drying in a gas atmosphere containing PF5.

Abstract: The present invention provides a method for purifying a niobium compound and/or tantalum compound in a simplified manner at a low cost. This is accomplished by providing a method for purifying a niobium compound and/or tantalum compound whereby a niobium compound and/or tantalum compound dissolved in a solvent is allowed to precipitate to be isolated.

Abstract: An object of the present invention is to provide a method for purifying a highly pure niobium compound and/or tantalum compound, the method enabling the purification of a highly pure niobium compound and tantalum compound in a simplified manner at a low cost. The object is met by providing a method comprising adding an organic solvent to an aqueous solution containing a niobium compound and/or tantalum compound together with impurities, and then performing extraction via the solution. A niobium compound and/or tantalum compound dissolved in a solution is allowed to precipitate, and said aqueous solution is obtained by dissolving the precipitate in water.

Abstract: A method for purifying tungsten hexafluoride of high purity, capable of producing tungsten hexafluoride of higher purity than that of the related art, readily and at a low cost. A method for purifying tungsten hexafluoride of high purity, characterized in that tungsten hexafluoride containing molybdenum hexafluoride as an impurity, makes contact with a layer, in which a metal or an alloy is packed, containing at least one of molybdenum, tungsten, copper, nickel, iron, cobalt, zinc, titanium, aluminum, calcium, and magnesium at a temperature ranging from 0° C. to 100° C.

Abstract: A method of purifying lithium hexafluorophosphate that allows to purify lithium hexafluorophosphate, useful as lithium secondary cell electrolyte, organic synthesis medium or the like, to an extremely high purity is provided. Lithium hexafluorophosphate containing harmful impurities such as oxyfluoride, lithium fluoride is purified by adding phosphoric chloride. The purification is performed in the presence of phosphoric chloride and hydrogen fluoride of the quantity equal or superior to the equivalent amount for reacting them, and then by converting lithium fluoride lithium hexafluorophosphate with generated phosphor pentafluoride.

Abstract: A method of purifying lithium hexafluorophosphate that allows to purify lithium hexafluorophosphate, useful as lithium secondary cell electrolyte, organic synthesis medium or the like, to an extremely high purity is provided. Lithium hexafluorophosphate containing harmful impurities such as oxyfluoride, lithium fluoride is purified by adding phosphoric chloride. The purification is performed in the presence of phosphoric chloride and hydrogen fluoride of the quantity equal or superior to the equivalent amount for reacting them, and then by converting lithium fluoride lithium hexafluorophosphate with generated phosphor pentafluoride.

Abstract: To provide a method for purifying tungsten hexafluoride of high purity, capable of producing tungsten hexafluoride of higher purity than that of the related art, readily and at a low cost.

Abstract: In order to provide a method for producing lithium hexafluorophosphate capable of producing lithium hexafluorophosphate of a higher purity than in the related art without the necessity for after-treatment for removal of impurities, a method is characterized by filtering lithium hexafluorophosphate coexisting with a solvent and then carrying out after-filtering drying in a gas atmosphere containing PF5.