Patent ID: 7790919

Claim:
A method for removing a hydrocarbon impurity from an acetic acid production process, said method comprising: (a) reacting methanol and carbon monoxide in the presence of a carbonylation catalyst, a catalyst stabilizer, methyl iodide, water and methyl acetate to produce an acetic acid stream containing a hydrocarbon impurity; (b) flashing at least a portion of the acetic acid stream into a vapor stream comprising acetic acid, water, methanol, methyl acetate, methyl iodide and the hydrocarbon impurity, and a liquid stream comprising the catalyst and the catalyst stabilizer; (c) separating the vapor stream from step (b) by distillation into a product stream comprising acetic acid and a minor amount of water, and an overhead stream comprising methyl iodide, water, methyl acetate, acetic acid and the hydrocarbon impurity; (d) condensing and separating the overhead stream from step (c) into a light, aqueous phase comprising water, acetic acid, and methyl acetate, and a heavy, organic phase comprising methyl iodide, acetic acid, methyl acetate, and the hydrocarbon impurity; and (e) distilling at least a portion of the heavy, organic phase from step (d) into a vapor stream comprising the majority of methyl iodide and a bottoms stream comprising the majority of acetic acid, methyl acetate, methyl iodide, and the hydrocarbon impurity; (f) extracting the bottoms stream from step (e) with water, an acetic acid aqueous solution, or with a methanol aqueous solution, and forming an organic phase comprising the majority of the hydrocarbon impurity and an aqueous phase comprising the majority of water, acetic acid, methyl iodide, and optional methanol; and (g) recycling the aqueous phase from step (f) to the carbonylation reaction of step (a).