METHOD AND APPARATUS FOR PRODUCING ACETIC ACID WITH IMPROVED PURIFICATION Russian patent published in 2013 - IPC C07C51/12 B01D3/00 C07C53/08 C07C51/44 

FIELD: chemistry.

SUBSTANCE: invention relates to improved carbonylation methods in order to produce acetic acid, the methods involving: (a) carbonylating methanol or reactive derivatives thereof in the presence of water, a catalyst selected from a group which includes rhodium catalysts, iridium catalysts and mixtures thereof, and methyl iodide as a promoter to form an acetic acid containing reaction mixture in the reactor; (b) separating the stream of the acetic acid containing reaction mixture into a liquid recycled stream and a crude product stream containing acetic acid, methyl iodide, methyl acetate and water; (c) feeding the crude product stream to a stripping column having a distillation zone; (d) purifying the crude product stream in the distillation zone of the stripping column to remove methyl iodide and methyl acetate and obtain a purified product stream, the purified product stream characterised lower concentration of methyl iodide and methyl acetate than the crude product stream, and wherein the step of purifying the crude product stream involves: (i) condensing overhead vapour from the distillation zone of the stripping column, (ii) decanting the condensed vapour to obtain a heavy phase mainly containing methyl iodide and a light phase mainly containing acetic acid and water, and (iii) refluxing at least a portion of the condensed heavy phase to the distillation zone of the stripping column; and (iv) recycling the light phase into the reactor; and (e) drawing a purified product stream from the stripping column.

EFFECT: content of acetic acid in the overhead vapour of the stripping column and content of water in the product stream of the stripping column (side cut) is reduced, which increases efficiency of purification.

17 cl, 3 dwg, 1 tbl