Method of accelerating methanol carbonylation

A method for producing acetic acid by heterogeneous carbonylation of methanol with carbon monoxide in a reaction liquid in the presence of alkyl iodide and a solid catalyst containing rhodium and including hydrolysis of methyl acetate,

• wherein the hydrolysis of the methyl acetate is accelerated by an acid having an acid dissociation constant (pKa) smaller than the constant of acetic acid, that acid being co-existent with the solid catalyst in the reaction system;
• wherein the carbonylation of methanol is performed in a region where liquid reaction product has a carbonylation degree Ca not lower than 0.7 mol/mol;
• and
• wherein the rhodium is supported on a carrier comprising a sulfonated copolymer of 4-vinylpyridine, styrene, and divinylbenzene.