Processes for Producing Acetic Acid

Patent metadata

Field	Value
Publication number	US-2016289154-A1
Application number	US-201514873636-A
Country	US
Kind code	A1
Filing date	Oct 2, 2015
Priority date	Apr 1, 2015
Publication date	Oct 6, 2016
Grant date	—

Abstract

Processes for the producing acetic acid and, in particular, to improved processes for removing a cation, such as lithium, and iodides from a low energy carbonylation process to produce purified acetic acid. In one embodiment, the cation, e.g., lithium, may be removed using a cationic exchanger prior to removing iodides using a metal-exchanged ion exchange resin. The present invention is also suited for removing at least one cation selected from the group consisting of Groups IA and IIA of the periodic table, quaternary nitrogen cations, and phosphorous-containing cations.

First claim

We claim:

1 . A process for producing acetic acid comprising:
carbonylating at least one member selected from the group consisting of methanol, dimethyl ether, and methyl acetate in the presence of water in an amount from 0.1 to 14 wt. %, a rhodium catalyst, methyl iodide, and a lithium compound, to form a reaction medium in a reactor; separating the reaction medium to form a liquid recycle stream and a vapor product stream; separating the vapor product stream in up to 2 distillation columns in a primary purification train to produce a crude acid product comprising acetic acid and lithium; contacting the crude acetic acid product with a cationic exchanger in the acid form to produce an intermediate acid product; and contacting the intermediate acetic acid product with a metal-exchanged ion exchange resin having acid cation exchange sites to produce a purified acetic acid.

2 . The process of claim 1 , wherein the lithium in the crude acid product is derived from and/or generated by the lithium compound in the reaction medium.

3 . The process of claim 1 , wherein the crude acid product comprises lithium in an amount of less than or equal to 10 wppm.

4 . The process of claim 1 , wherein the crude acid product comprises water in an amount of less than or equal to 0.2 wt. %.

5 . The process of claim 1 , wherein the intermediate acetic acid product comprises less lithium than the crude acetic acid product.

6 . The process of claim 1 , wherein the intermediate acid product comprises lithium in an amount of less than or equal to 100 wppb.

7 . The process of claim 1 , wherein the purified acetic acid comprises lithium in an amount of less than or equal to 100 wppb.

8 . The process of claim 1 , wherein the purified acetic acid comprises a metal displaced from the metal-exchanged ion exchange resin in an amount of less than or equal to 100 wppb.

9 . The process of claim 1 , wherein the purified acetic acid comprises iodides in an amount of less than or equal to 100 wppb.

10 . The process of claim 1 , wherein the vapor product stream is separated in 2 distillation columns in the primary purification train.

11 . The process of claim 1 , wherein the cationic exchanger in the acid form comprises a resin of acid-form strong acid cation exchange macroreticular, macroporous or mesoporous resins.

12 . The process of claim 1 , further comprising a step of adding a potassium salt selected from the group consisting of potassium acetate, potassium carbonate, and potassium hydroxide to the distilled acetic acid product prior to distilling the distilled acetic acid product in a second distillation column; wherein at least a portion of the potassium is removed by the cationic exchanger in the acid form.

13 . The process of claim 1 , further comprising adjusting the temperature of the crude acetic acid product to from 50° C. to 120° C.

14 . The process of claim 1 , further comprising adjusting the temperature of the intermediate acetic acid product to from 50° C. to 85° C.

15 . The process of claim 1 , wherein separating the vapor product stream comprises:
distilling the vapor product stream in a first distillation column to form a sidedraw comprising acetic acid; and distilling the sidedraw in a second distillation column to produce a crude acid product comprising acetic acid and lithium.

16 . The process of claim 15 , wherein the crude acid product is removed from a side stream port at a position above the bottom of the second distillation column.

17 . The process of claim 16 , wherein the side stream is a liquid stream.

18 . The process of claim 15 , wherein the crude acid product is removed as a residue from the bottom of the second distillation column.

19 . The process of claim 15 , further comprising condensing an low boiling point overhead obtained from the first distillation column to form a heavy liquid phase and a light liquid phase, and wherein a portion of the heavy liquid phase is treated to remove at least one permanganate reducing compound selected from the group consisting of acetaldehyde, acetone, methyl ethyl ketone, butylaldehyde, crotonaldehyde, 2-ethyl crotonaldehyde, 2-ethyl butyraldehyde, and the aldol condensation products thereof.

20 . The process of claim 1 , wherein metal-exchanged ion exchange resin comprises at least one metal selected from the group consisting of silver, mercury, palladium and rhodium.

21 . The process of claim 1 , wherein at least 1% of the strong acid exchange sites of said metal-exchanged resin are occupied by silver.

Assignees

• Celanese Int Corp

Inventors

• Scates Mark O
• Abrego Sarah Lane
• Liu Yaw-Hwa
• Shaver Ronald D

Classifications

• C07C51/12 Primary

  on an oxygen-containing group in organic compounds, e.g. alcohols · CPC title

• C07C51/47

  by solid-liquid treatment; by chemisorption · CPC title

• B01D15/362

  Cation-exchange · CPC title

• C07C51/44

  by distillation · CPC title