Patent ID: 10183905

Abstract:
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.