PROCESS OF PRODUCING ACETIC ACID VIA CARBONYLATION OF METHANOL Russian patent published in 2004 - IPC

FIELD: industrial organic synthesis.

SUBSTANCE: production of acetic acid via carbonylation of methanol on rhodium carbonylation catalyst is accomplished at total reaction mixture pressure 15-40 atm (1520-4050 kPa) and concentration of hydrogen in carbon monoxide between about 0.001 and about 25 mol % while maintaining partial pressure of hydrogen between about 0.1 and 3.5 psi (10.3-24.1 kPa). Effective rhodium concentration in reaction mixture is at least 500 ppm. Reaction mixture further includes between about 1 to 20 wt % methyl iodide and between about 0.5 and 30 wt % methyl acetate. Catalyst is stabilized and co-promoted by an efficient salt, which is soluble in reaction mixture at reaction temperature, in amounts required to maintain iodide ion concentration between about 2 and about 20 wt %. This salt is selected from quaternary ammonium salts, phosphonium salts, and group IA and IIA metal salts. Stability of catalyst and productivity of system are achieved by maintaining a limited concentration of water in reaction mixture (from about 0.1 to at least 14 wt %). Alternatively, production of acetic acid is accomplished by reaction of methanol with carbon monoxide in presence of effective amount of rhodium in reaction mixture (at least 500 ppm), stability of catalyst and productivity of system being maintained by about 0.5 to 30 wt % methyl acetate, about 0.1 to about 19 wt % water together with salt, which were effective as stabilizer and co-promoter of catalyst and soluble in reaction mixture at reaction temperature in amounts required to maintain iodide ion concentration between about 2 and about 20 wt %. In this case, partial pressure of hydrogen between ranges from about 0.1 to 3.5 psi while total pressure of reaction mixture is 1520 to 4050 kPa. Concentration of hydrogen in carbon monoxide ranges from about 0.001 to below 0.25 mol %.

EFFECT: reduced formation of undesired carbonyl compound impurities at optimal productivity of system and reduced investments.

17 cl, 2 tbl, 4 ex