Removing hydrocarbon impurities from acetic acid production intermediate
View Patent ↗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.
1. A method for removing impurities from an acetic acid production process comprising the steps of:
removing a hydrocarbon impurity from an acetic acid production intermediate wherein the removing step further comprises the step of:
extracting the acetic acid production intermediate with a hydrocarbon extracting agent to form:
a light, aqueous phase comprising the hydrocarbon impurity and the extracting agent; and,
a heavy, organic phase comprising acetic acid and methyl iodide,
wherein the hydrocarbon extracting agent is a C 11 to C 20 aromatic or paraffinic hydrocarbon, and
wherein the acetic acid production intermediate is an alkane distillation bottoms stream wherein the alkane distillation bottoms stream is composed of by weight percent a majority of acetic acid and the hydrocarbon impurity.
2. The method of claim 1 , wherein the hydrocarbon impurity is selected from the group consisting of alkanes, alkenes, aromatics, and mixtures thereof.
3. The method of claim 2 , wherein the alkane is a C 3 -C 12 alkane.
4. The method of claim 1 , wherein the intermediate comprises methyl iodide, acetic acid, methyl acetate and the hydrocarbon impurity.
5. The method of claim 1 , comprising adding water to the extraction.
6. The method of claim 5 wherein the water is added to the extraction in an amount of 5% to 50% by volume of the hydrocarbon extracting agent.
7. The method of claim 1 wherein the ratio of the hydrocarbon extracting agent to the alkane distillation bottom stream is 25/75 to 75/25 (V/V).
8. The method of claim 1 wherein the hydrocarbon extracting agent is selected from the group consisting of pentadecane and dodecane.
9. The method of claim 1 wherein the heavy phase comprises greater than 15 wt % methyl iodide.
10. The method of claim 5 wherein the light phase comprises less than 5 wt % acetic acid.