Patent ID: 8309761

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 methyl iodide and a bottoms stream comprising acetic acid, methyl acetate, methyl iodide, and the hydrocarbon impurity; and (f) extracting the bottoms stream of step (e) with an hydrophilic imidazolium salt, wherein the hydrophilic imidazolium salt has the general structure: wherein x⊖ is a counter ion and R 1 , R 2 , R 3 , R 4 and R 5 are independently selected from the consisting of hydrogen and C 1 -C 6 hydrocarbon substitutes, and forming a light phase comprising the hydrocarbon impurity and a heavy phase comprising the ionic liquid, acetic acid, and methyl iodide.