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.

A highly unsaturated fatty acid or a highly unsaturated fatty acid ethyl ester that has been produced using as a feedstock oil a fat or oil that contains highly unsaturated fatty acids as constituent fatty acids and which has been reduced in the contents of environmental pollutants, wherein among the dioxins contained, polychlorinated dibenzoparadioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) are contained in amounts of less than 0.05 pg-TEQ/g and coplanar PCBs (Co-PCBs) in amounts of less than 0.03 pg-TEQ/g. Also disclosed is a method for producing the highly unsaturated fatty acid or highly unsaturated fatty acid ethyl ester by the steps of removing free fatty acids and environmental pollutants by thin-film distillation from a feedstock oil, ethyl esterifying the resulting fat or oil, and refining the same by rectification and column chromatography.

The present invention relates to a method of redissociating Michael adducts of acrylic acid present in a liquid F in a redissociation apparatus comprising at least one separating column K, an evaporator V and a pump P, wherein, in the event of an unwanted rise in the viscosity of the residue R in the bottom space of the separating column K, the feed of the liquid F into the redissociation apparatus is stopped, the residue R in the bottom space of the separating column K is diluted and cooled with a solvent 1, and the bottom space of the separating column K is emptied.

The present invention relates to a method of redissociating Michael adducts of acrylic acid present in a liquid F in a redissociation apparatus comprising at least one separating column K, an evaporator V and a pump P, wherein, in the event of an unwanted rise in the viscosity of the residue R in the bottom space of the separating column K, the feed of the liquid F into the redissociation apparatus is stopped, the residue R in the bottom space of the separating column K is diluted and cooled with a solvent 1, and the bottom space of the separating column K is emptied.

The present invention relates to a method of redissociating Michael adducts of acrylic acid present in a liquid F in a redissociation apparatus comprising at least one separating column K, an evaporator V and a pump P, wherein, in the event of an unwanted rise in the viscosity of the residue R in the bottom space of the separating column K, the feed of the liquid F into the redissociation apparatus is stopped, the residue R in the bottom space of the separating column K is diluted and cooled with a solvent 1, and the bottom space of the separating column K is emptied.

The present invention relates to an improved process for the regeneration, by thermal cracking, of a mixture of heavy byproducts (residues) resulting from a unit for the production of acrylic acid and from a unit for the production of acrylic ester, resulting in acrylic acid, acrylic esters and alcohols being obtained, for the purpose of recycling them in the plant for the production of the acrylic ester.

The present invention relates to an improved process for the regeneration, by thermal cracking, of a mixture of heavy byproducts (residues) resulting from a unit for the production of acrylic acid and from a unit for the production of acrylic ester, resulting in acrylic acid, acrylic esters and alcohols being obtained, for the purpose of recycling them in the plant for the production of the acrylic ester.

The present invention relates to an improved process for the regeneration, by thermal cracking, of a mixture of heavy byproducts (residues) resulting from a unit for the production of acrylic acid and from a unit for the production of acrylic ester, resulting in acrylic acid, acrylic esters and alcohols being obtained, for the purpose of recycling them in the plant for the production of the acrylic ester.

Provided is a process for producing acrylic acid, wherein the process comprises a first step and a second step in which a first absorbent is added to a reaction product of a bio-material and cooled to separate a first low-boiling-point material including acetaldehyde (ACHO) and a first high-boiling-point material including acrylic acid (AA). The process is capable of producing high-purity acrylic acid at high yield, and acetaldehyde is produced as by-product along with the reaction product of the bio-material. The process includes separating the acetaldehyde produced as by-product into a high-purity product at high yield.