Provided is a method for easily and safely removing, from a reactor, a catalyst used in a reaction that is performed using hydrogen fluoride in the presence of the catalyst. In a reaction performed in a reactor containing at least hydrogen fluoride and a catalyst, the catalyst is removed through a process comprising a heating step of performing heat-treatment so that the ambient temperature of the reactor is 80° C. or more after completion of the reaction, and a purge step of flowing inert gas into the reactor to discharge the hydrogen fluoride to the outside of the reactor after completion of the reaction.

A method produces acetic acid and includes a reaction step, a first purification step, a second purification step, and a third purification step. In the reaction step, a material mixture including methanol, carbon monoxide, a catalyst, and an iodide is subjected to a methanol carbonylation reaction in a reactor (1) to form acetic acid. In the first purification step, a crude acetic acid stream including acetic acid formed in the reaction step is subjected to distillation in a distillation column (3) to give a first acetic acid stream enriched with acetic acid. In the second purification step, the first acetic acid stream is subjected to distillation in a distillation column (5) to give a second acetic acid stream further enriched with acetic acid. In the third purification step, an acetic acid stream is subjected to purification in an additional purification unit (e.g., a distillation column (6)) while controlling the corrosive iodine concentration in the acetic acid stream passing through the unit to 100 ppm or less, to give a third acetic acid stream still further enriched with acetic acid. The method for producing acetic acid is suitable for restraining corrosion of the acetic acid production equipment.

A method produces acetic acid and includes a reaction step, a first purification step, a second purification step, and a third purification step. In the reaction step, a material mixture including methanol, carbon monoxide, a catalyst, and an iodide is subjected to a methanol carbonylation reaction in a reactor (1) to form acetic acid. In the first purification step, a crude acetic acid stream including acetic acid formed in the reaction step is subjected to distillation in a distillation column (3) to give a first acetic acid stream enriched with acetic acid. In the second purification step, the first acetic acid stream is subjected to distillation in a distillation column (5) to give a second acetic acid stream further enriched with acetic acid. In the third purification step, an acetic acid stream is subjected to purification in an additional purification unit (e.g., a distillation column (6)) while controlling the corrosive iodine concentration in the acetic acid stream passing through the unit to 100 ppm or less, to give a third acetic acid stream still further enriched with acetic acid. The method for producing acetic acid is suitable for restraining corrosion of the acetic acid production equipment.

The purpose of the present invention is to provide: composite phthalocyanine microparticles of a nano-order level, preferably on the order of 100 nm, that are optimal as a coloring material; and a method for producing the same. Provided is a method for producing composite phthalocyanine microparticles, the method being characterized by including a step (1) for preparing a dissolved solution by dissolving at least copper phthalocyanine and titanyl phthalocyanine and/or cobalt phthalocyanine as raw materials in a first solvent, a step (2) for precipitating composite phthalocyanine by mixing the dissolved solution obtained in step (1) with a second solvent that serves as a poor solvent of the abovementioned raw materials, and a step (3) for causing an organic solvent to act on the composite phthalocyanine obtained in step (2). Also provided are composite phthalocyanine microparticles containing at least copper phthalocyanine and titanyl phthalocyanine and/or cobalt phthalocyanine, the composite phthalocyanine microparticles having an aspect ratio of 1.1-2.5 and a particle size of 5-100 nm.

[Problem to be Solved]

To provide a method for preparing a catalyst that has high activity and exhibits high durability with reduced elution of a catalyst metal when a liquid-phase oxidation reaction is brought about without combined use of an alkali; and a method for producing an oxide highly efficiently by use of the catalyst.

The method for preparing a catalyst has the following Steps 1, 2 and 3.

Step 1: preparing an aqueous dispersion of a catalyst carrying Pt on activated carbon;

Step 2: preparing an aqueous solution containing Bi in an ionic state; and

Step 3: adding the aqueous dispersion obtained in Step 1 to the aqueous solution obtained in Step 2.

An object of a first aspect of the present invention is to provide a radical generating catalyst that can generate (produce) radicals under mild conditions. In order to achieve the above object, a first radical generating catalyst according to the first aspect of the present invention is characterized in that it includes ammonium and/or a salt thereof. A second radical generating catalyst according to the first aspect of the present invention is characterized in that it includes an organic compound having Lewis acidic properties and/or Brønsted acidic properties.

An object of a first aspect of the present invention is to provide a radical generating catalyst that can generate (produce) radicals under mild conditions. In order to achieve the above object, a first radical generating catalyst according to the first aspect of the present invention is characterized in that it includes ammonium and/or a salt thereof. A second radical generating catalyst according to the first aspect of the present invention is characterized in that it includes an organic compound having Lewis acidic properties and/or Brønsted acidic properties.

A butadiene production system and a butadiene production method are provided in which the yield is high and environmental load can be reduced. The butadiene production system (1) includes: a gas preparation device (10) that heats raw materials to prepare a mixed gas including hydrogen and carbon monoxide; an ethanol production device (12) that is provided downstream of the gas preparation device (10) and brings the mixed gas into contact with a first catalyst to obtain ethanol; a butadiene production device (16) that is provided downstream of the ethanol production device (12) and brings the ethanol into contact with a second catalyst to obtain butadiene; and return means (18) for returning hydrogen, ethylene, and the like, which are produced as by-products in the butadiene production device (16), to the gas preparation device (10). In addition, in the butadiene production method, the butadiene production system (1) is used.

A method for synthesizing a hydrocarbon by reducing carbon dioxide in water, said method comprising supplying oxygen to water containing carbon dioxide to generate oxygen nanobubbles, irradiating the water containing the oxygen nanobubbles with ultraviolet light in the presence of a photocatalyst to generate active oxygen, and reducing carbon dioxide in the presence of the active oxygen.

A butadiene production system and a butadiene production method are provided in which butadiene can be produced with a high yield. The butadiene production system (1) includes: a gas preparation device (10) that heats raw materials to prepare a mixed gas including hydrogen and carbon monoxide; an ethanol production device (12) that is provided downstream of the gas preparation device (10) and brings the mixed gas including hydrogen and carbon monoxide into contact with a first catalyst to obtain ethanol; a butadiene production device (16) that is provided downstream of the ethanol production device (12) and brings the ethanol into contact with a second catalyst to obtain butadiene; and return means (18) for returning hydrogen, which is produced as a by-product in the butadiene production device (16), to the ethanol production device (12). In addition, in the butadiene production method, the butadiene production system (1) is used.