PRODUCING ACETIC ACID BY CARBONYLATION WITH HIGH REACTIVITY AND FLASH EVAPORATION Russian patent published in 2013 - IPC C07C51/12 C07C51/44 C07C53/08 

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method of producing acetic acid, involving (a) catalytic reaction of methanol or reactive derivative thereof with carbon monoxide in the presence of a group VIII metal based homogeneous catalyst and methyl iodide as a promoter in a reaction vessel which contains a liquid reaction mixture containing acetic acid, water, methyl acetate, methyl iodide and a homogeneous catalyst, wherein the reaction vessel operates at reactor pressure; (b) removing the reaction mixture from the reaction vessel and feeding the removed reaction mixture along with additional carbon monoxide into a pre-evaporation/post-reaction vessel operating at low pressure, which is below the pressure in the reaction vessel; (c) blowing light fractions in the pre-evaporation vessel and simultaneous consumption of methyl acetate in the pre-evaporation/post-reaction vessel to obtain a pre-evaporation mixture which is rich in acetic acid and is poor in methyl iodide and methyl acetate compared to the reaction mixture; (d) removing the pre-evaporation reaction mixture from the pre-evaporation/post-reaction vessel and feeding the pre-evaporation mixture into the evaporation vessel; (e) flash evaporation of the stream of raw acetic acid from the mixture in the evaporation vessel operating at pressure which is considerably lower than that of the pre-evaporation/post-reaction vessel; (f) recycling the residue after evaporation process from the evaporation vessel into the reaction vessel and (g) purifying the stream of the raw product. Low content of methyl iodide and methyl acetate in the formed stream of evaporated raw product eliminate the role of light fraction columns as the bottleneck of the scheme.

EFFECT: method increases efficiency of the process; eliminated the need for a high-pressure absorber, which reduces capital costs and operating costs.

24 cl, 1 dwg