Process for making acetic anhydride and, if desired, acetic acid

Abstract From the Canadian patent

Acetic anhydride and acetic acid are made by reacting methyl acetate and/or dimethylether and if desired, methanol, with carbon monoxide optionally in the presence of water, at temperatures of 350 to 575 K, under pressures of 1 to 300 bar in the presence of a catalyst system containing noble metals belonging to group VIII of the Periodic System of the elements or their compounds, iodine and/or its compounds and if, desired, carbonyl-yielding non noble metals of groups IV V, VI, VII or VIII of the Periodic system of the elements or, their compounds and, if desired, an aliphatic carboxylic acid having from 1 to 4 carbon atoms. To this end a catalyst, system containing tetrabutylphosphonium …