METHOD OF PRODUCING ACETIC ACID Russian patent published in 2012 - IPC C07C51/12 C07C53/08 G01N21/35 B01J19/12 G01N21/31 

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method of producing acetic acid comprising the following steps: (a) carbonylation of methanol and/or reactive derivative thereof with carbon monoxide in a first reaction zone containing a liquid reaction mixture which contains a carbonylation catalyst and a promoter metal for the carbonylation catalyst, methyl iodide, methyl acetate, acetic acid and optionally water, where the liquid reaction mixture contains, in equilibrium, at least a first soluble catalytic material with a promoter metal and a second soluble catalytic material with a promoter metal, wherein among the materials which are in equilibrium, the first catalytic material with a promoter metal is the least promoter active; (b) outputting from said first reaction zone the liquid reaction mixture together with dissolved and/or trapped carbon monoxide and other gases; (c) optionally passing said output liquid reaction mixture through one or more successive reaction zones for using up at least a portion of the dissolved and/or trapped carbon monoxide; (d) directing said liquid reaction mixture from step (b) and optional step (c) to one or more steps for separation through single equilibrium evaporation to obtain a vapour fraction which contains condensable components and a low-pressure exhaust gas, where the condensable components contain the obtained acetic acid, methyl iodide, methyl acetate and optionally water, and the low-pressure exhaust gas contains carbon monoxide and other gases which are dissolved and/or trapped by the output liquid reaction mixture; and a liquid fraction which contains the carbonylation catalyst, the promoter metal for the carbonylation catalyst and acetic acid as a solvent; (e) returning the liquid fraction from the step for separation through single equilibrium evaporation to the first reaction zone; (f) determining (I) concentration of the first catalytic material with a promoter metal and/or (II) the ratio of concentration of the first catalytic material with a promoter metal to concentration of the second catalytic material with a promoter metal which are in equilibrium with each other, contained in the liquid reaction mixture at any of steps (a) to (d) and/or contained in the liquid fraction at step (e); and (g) maintaining (I) and/or (II) lower than a predetermined value.

EFFECT: present invention enables to optimise the process of producing acetic acid through carbonylation of methanol and/or a reactive derivative by maintaining concentration of the first catalytic material and/or the ratio of concentration of the first to the second catalytic material lower than a value where the negative effect could have been on one or more of such parameters as rate of reaction, selectivity, stability or service life of the catalyst.

13 cl 1 dwg, 2 ex, 1 tbl