Patent ID: 8283493
Filing Date: 2012-10-09
Classification: C07C

Abstract:
1. A process for the production of acetic acid which process comprises the steps of: (a) introducing methanol, methyl acetate, dimethyl ether and/or methyl iodide and carbon monoxide into a first reaction zone containing a liquid reaction composition comprising a carbonylation catalyst, optionally a carbonylation catalyst promoter, methyl iodide, methyl acetate, acetic acid and water; (b) withdrawing at least a portion of the liquid reaction composition together with dissolved and/or entrained carbon monoxide and other gases from the first reaction zone; (c) passing at least a portion of the withdrawn liquid reaction composition to a second reaction zone, wherein at least a portion of the dissolved and/or entrained carbon monoxide is consumed; (d) passing at least a portion of the liquid reaction composition from the second reaction zone into a flash separation zone to form a vapour fraction, which comprises acetic acid, methyl iodide, methyl acetate and low pressure off-gas, comprising carbon monoxide; and a liquid fraction, which comprises carbonylation catalyst and optional carbonylation catalyst promoter; (e) passing the vapour fraction from the flash separation zone to one or more distillation zones to recover acetic acid product; (f) recycling at least a portion of the liquid fraction from the flash separation zone to the first reaction zone; wherein the temperature of the liquid reaction composition withdrawn from the first reaction zone is in the range of 170 to 195° C.; and the temperature of the liquid reaction composition passed from the second reaction zone to the flash separation zone is at least 8° C. greater than the temperature of the liquid reaction composition withdrawn from the first reaction zone.