Removing hydrocarbon impurities from acetic acid production intermediate
AssigneeLyondellBasell Acetyls, LLC
InventorsNoel Hallinan, Brian A. Salisbury, Shao-hua Guo
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Abstract
A method for removing hydrocarbon impurities from an acetic acid production intermediate is disclosed. The method comprises extracting the intermediate with a hydrocarbon extracting agent. The extraction is preferably performed with the alkane distillation bottom stream which comprises methyl iodide, acetic acid, and hydrocarbon impurities. The extraction forms a light phase which comprises the hydrocarbon impurity and the extracting agent and a heavy phase which comprises methyl iodide and acetic acid. The extraction heavy phase is optionally recycled to the alkane distillation or to the carbonylation reaction.
Claims6
A method for producing acetic acid 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 comprising a hydrocarbon impurity;
- (b) flashing 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 water, and an overhead stream,
- wherein the overhead stream comprises:
- (i) from about 60 to 90 wt. % methyl iodide,
- (ii) water,
- (iii) methyl acetate,
- (iv) acetic acid, and
- (v) the hydrocarbon impurity;
- (d) condensing the overhead stream from step (c) into a light, aqueous phase comprising water, and acetic acid, methyl acetate, and a heavy, organic phase comprising methyl iodide, acetic acid, water, and the hydrocarbon impurity;
- and
- (e) distilling the heavy, organic phase from step (d) into a vapor stream comprising methyl iodide and a bottoms stream comprising acetic acid, methyl iodide, water, and the hydrocarbon impurity;
- and
- (f) extracting the bottoms stream from step (e) with a mixture comprising about 50 to about 95%, by volume, of a hydrocarbon extracting agent and about 5 to about 50%, by volume, of water, and forming a light phase comprising the hydrocarbon impurity and the extracting agent and a heavy phase comprising methyl iodide, water, and acetic acid
- wherein the hydrocarbon extracting agent is a C9 to C20 aromatic or paraffinic hyrdocarbon.
Dependencies are inferred from the claim text.