| 摘要 |
FIELD: chemistry.SUBSTANCE: invention relates to an improved method of producing acetic acid comprising the following steps: reacting methanol with carbon monoxide in a reaction vessel containing water, methyl iodide and methyl acetate in the presence of a group VIII metal based carbonylation catalyst; separating products of said reaction into a volatile product phase containing acetic acid and a less volatile phase; distilling said volatile phase in a distillation apparatus to obtain a purified product of acetic acid and a first overhead fraction containing methyl iodide and acetaldehyde; condensing at least a portion of said overhead fraction; measuring density of said condensed first overhead fraction; determining relative concentration of methyl iodide, acetaldehyde or both in the first overhead fraction based on the measured density; and adjusting at least one process control parameter associated with distillation of said volatile phase as a response reaction to said relative concentration. The invention relates to a method of producing acetic acid comprising the following steps: reacting methanol with carbon monoxide in a reaction medium containing water and methyl iodide in the presence of a group VIII metal based carbonylation catalyst; performing vapour-liquid separation in said reaction medium to obtain a vapour phase containing acetic acid, methyl iodide, acetaldehyde and water, and a liquid phase; distilling said vapour phase in a distillation apparatus to obtain a purified acetic acid product and at least a first overhead fraction containing acetaldehyde and methyl iodide; condensing said first overhead fraction; extracting said first overhead fraction with water to obtain a raffinate containing methyl iodide and an aqueous extract; measuring density of at least one stream selected from a group consisting of said first overhead fraction, said raffinate and said aqueous extract; determining relative concentration of methyl iodide, acetaldehyde or both in at least said first overhead fraction, said raffinate and said aqueous extract based on the measured density; and adjusting at least one process control parameter associated with either distillation of said vapour phase or extraction of said first overhead fraction as a response reaction to said relative concentration.EFFECT: method of controlling the separation process in order to remove permanganate reduced compounds from a process stream during methanol carbonylation, involving steps of measuring density of a stream containing acetaldehyde and methyl iodide, and calculating relative concentration of acetaldehyde and methyl iodide in the stream enables to adjust parameters of the distillation or extraction process based on measured density or one or more relative concentrations calculated therefrom.12 cl, 5 dwg |
