PROCESS FOR SIMULTANEOUS PREPARATION OF ACETIC ACID AND ACETIC ANHYDRIDE

A process for simultaneous production of acetic acid and acetic anhydride from a starting mixture of methanol and methyl acetate and optionally dimethyl ether by reaction with carbon monoxide in a reaction zone on a catalyst system under anhydrous conditions is specified, which is characterised in that a) the reaction is carried out in the presence of a catalyst system consisting of a base metal of group VIII of the Periodic Table, methyl iodide, an alkali metal, organophosphonium or organoammonium compound as promoter and optionally a compound of a base metal of groups IV to VII of the Periodic Table as co-promoter; b) a molar ratio of methanol to methyl acetate and optionally dimethyl ether of 10 : 1 to 1 : 10 as starting mixture is employed and c) the reaction is carried out under a pressure of 25 to 200 bar and at a temperature of 150 to 250 DEG C. n