Catalyst stability and corrosion prevention in acetic acid production process

Abstract

Processes for producing acetic acid herein generally include contacting methanol and carbon monoxide in the presence of a reaction medium under carbonylation conditions sufficient to form acetic acid, the reaction medium including a carbonylation catalyst selected from rhodium catalysts, iridium catalysts and palladium catalysts; from 1 wt. % to 14 wt. % water; and a plurality of additives, in-situ generated derivatives of the plurality of additives or combinations thereof; the plurality of additives including a first additive including one or more phosphine oxides and a second additive selected from heteropolyacids, metal salts and combinations thereof, the heteropolyacids represented by the formula HMXO, wherein H is hydrogen, M is selected from tungsten and molybdenum, X is selected from phosphorous and silicon and O is oxygen and n is 3 or 4, the metal salts are selected from transition metal salts, lanthanide metal salts and combinations thereof; and recovering acetic acid from the process.