FIELD: chemistry.
SUBSTANCE: invention relates to a method of producing acetic acid, which is conversion of methanol and its reactive derivative in the presence of carbon monoxide and a rhodium-based catalyst system consisting of: (i) rhodium; (ii) a halogen promoter; (iii) an iodide salt as a co-promoter in concentration which ensures concentration of the iodide ion higher than 3 wt % of the reaction mixture; and (iv) a metal salt as a stabiliser, selected from a group consisting of ruthenium salts, tin salts and mixtures thereof; wherein the reaction mixture contains 0.1-14 wt % water; and wherein the ruthenium salt, tin salt or mixtures thereof are present in the reaction mixture in molar ratio of combined ruthenium and tin to rhodium between 0.1:1 and 20:1. The metal salt as a stabiliser minimises deposition of rhodium metal when extracting the product - acetic acid - particularly in an evaporation apparatus in the acetic acid separation process. Stability of rhodium metal is achieved even when producing acetic acid in a reaction mixture with low content of water in the presence of an iodide salt as a co-promoter in a concentration which ensures concentration of the iodide ion higher than approximately 3 wt % of the reaction mixture.
EFFECT: improved method of producing acetic acid via a catalytic carbonylation reaction.
8 cl, 2 dwg
