US-12623991-B2 - Removal of aldehydes in acetic acid production

US12623991B2US 12623991 B2US12623991 B2US 12623991B2US-12623991-B2

Abstract

A system and method for removing acetaldehyde from an acetic acid system, including providing a solution from the acetic acid system, the stream having methyl iodide and acetaldehyde, distilling the solution to produce an overhead stream having a higher concentration of acetaldehyde, contacting the overhead stream, and optionally a hydroxyl compound, with an acid catalyst to convert the acetaldehyde to an aldehyde derivative having a higher boiling point than acetaldehyde.

Inventors

Shane J. Weber
Noel C. Hallinan
Ryan J. Mathews

Assignees

LYONDELLBASELL ACETYLS, LLC

Dates

Publication Date: 20260512
Application Date: 20230214

Claims (11)

1 . A method for removing acetaldehyde from an acetic acid system, wherein the acetic acid system comprises a light-ends column and a decanter, the method comprising: feeding a light-ends overhead stream from the light-ends column to the decanter; withdrawing from the decanter: (i) a heavy organic phase stream, comprising methyl iodide, acetaldehyde, water, methyl acetate, and acetic acid; and (ii) a light aqueous phase stream comprising methyl iodide, acetaldehyde, water, methyl acetate, and acetic acid; and providing as a solution a portion of the heavy organic phase stream and/or a portion of the light aqueous phase stream, wherein the solution comprises acetic acid, water, methyl acetate, methyl iodide, and acetaldehyde, wherein the acetaldehyde is present in a first concentration based on the total weight of the solution; distilling the solution to form a first distillation overhead stream, comprising methyl iodide and acetaldehyde, wherein the acetaldehyde is present in a second concentration based on the total weight of the first distillation overhead stream, and the second concentration is greater than the first concentration; and contacting a reactive feed stream, comprising the first distillation overhead stream, and optionally a hydroxyl compound, with an acid catalyst to form a reacted stream, wherein contacting the reactive feed stream with the acid catalyst converts at least a portion of the acetaldehyde to an aldehyde derivative having a higher boiling point than acetaldehyde.
2 . The method of claim 1 , wherein the aldehyde derivative is crotonaldehyde, acetal, or a combination thereof.
3 . The method of claim 1 , wherein the hydroxyl compound comprises a C 2 -C 10 diol or triol.
4 . The method of claim 1 , further comprising removing the aldehyde derivative from the reacted stream.
5 . The method of claim 4 , wherein removing comprises: distilling the reacted stream to form a second distillation overhead stream and a second distillation bottoms stream, wherein the second distillation bottoms stream comprises a portion of the aldehyde derivative; and discharging the second distillation bottoms stream from the acetic acid system.
6 . The method of claim 5 , further comprising recycling the second distillation overhead stream within the acetic acid system.
7 . The method of claim 6 , wherein the acetic acid system comprises an acetic acid production reactor and an acetaldehyde reactor for contacting the reactive feed stream with the acid catalyst, and the second distillation overhead stream is recycled to the acetic acid production reactor, the acetaldehyde reactor, or a combination thereof.
8 . The method of claim 1 , wherein the solution comprises less than 1 wt % water.
9 . The method of claim 1 , wherein the solution comprises greater than 20 wt % water.
10 . The method of claim 1 , wherein the acetic acid system comprises an acetaldehyde reactor having a fixed bed comprising the acid catalyst, and the reactive feed stream is fed to the acetaldehyde reactor.
11 . The method of claim 1 , wherein the acid catalyst is an acidic ion exchange resin.

Description

PRIOR RELATED APPLICATIONS This application claims the benefit of priority to U.S. Provisional Application No. 63/309,928, filed on Feb. 14, 2022, the contents of which are incorporated herein by reference in their entirety. FIELD OF THE INVENTION This disclosure relates to the production of acetic acid. More particularly, the disclosure relates to removal of acetaldehyde in acetic acid production. BACKGROUND OF THE INVENTION In the current acetic acid production process, a reaction mixture is withdrawn from a reactor and is separated in a flash tank into a liquid fraction and a vapor fraction comprising acetic acid generated during the carbonylation reaction. The liquid fraction may be recycled to the carbonylation reactor, and the vapor fraction is passed to a separations unit, which by way of example may be a light-ends distillation column. The light-ends distillation column separates a crude acetic acid product from other components. The crude acetic acid product is passed to a drying column to remove water and then is subjected to further separations to recover acetic acid. One challenge facing the industry is the presence of aldehyde(s) in acetic acid production, which can be present in the feed and also form as an undesired byproduct of carbonylation reactions. Processes for removing aldehydes exist; however, there continues to be a need to improve upon, and provide alternatives to, current aldehyde removal processes. SUMMARY OF THE INVENTION An aspect of the disclosure relates to a method for removing acetaldehyde from an acetic acid system, including: providing a solution from the acetic acid system, the solution comprising methyl iodide and acetaldehyde; distilling the solution to produce an overhead stream having a higher concentration of acetaldehyde, and contacting the overhead stream, and optionally a hydroxyl compound, with an acid catalyst to convert the acetaldehyde to an aldehyde derivative having a higher boiling point that acetaldehyde. Another aspect of the disclosure relates to a method of operating an acetic acid production system, including: flashing a reaction mixture discharged from an acetic acid production reactor into a vapor stream and a liquid stream, the vapor stream comprising acetic acid, water, methanol, methyl acetate, methyl iodide, and acetaldehyde; distilling the vapor stream into a product stream of acetic acid and water, a first bottoms stream, and a first overhead stream comprising methyl iodide, water, methyl acetate, acetic acid, and acetaldehyde; condensing the first overhead stream into a light aqueous phase comprising water, acetic acid, and methyl acetate, and a heavy organic phase comprising methyl iodide, acetic acid, water, and acetaldehyde; distilling a portion of the light aqueous phase and/or a portion of the heavy organic phase to produce a second overhead stream comprising a higher concentration of acetaldehyde than the corresponding distillation feed stream; and contacting the second overhead stream with an acid catalyst to convert at least a portion of the acetaldehyde to an aldehyde derivative having a higher boiling point than acetaldehyde. Yet another aspect relates to a method of producing acetic acid, including: reacting methanol and carbon monoxide in the presence of a carbonylation catalyst to produce a crude stream comprising acetic acid; flashing the crude stream discharged from an acetic acid production reactor into a vapor stream and a liquid stream, the vapor stream comprising acetic acid, water, methanol, methyl acetate, methyl iodide, and acetaldehyde; distilling the vapor stream into a product stream of acetic acid and water, a first bottoms stream, and a first overhead stream comprising methyl iodide, water, methyl acetate, acetic acid, and acetaldehyde; condensing the first overhead stream into a light aqueous phase comprising water, acetic acid, and methyl acetate, and a heavy organic phase comprising methyl iodide, acetic acid, water, and acetaldehyde; distilling a portion of the light aqueous phase and/or a portion of the heavy organic phase to produce a second overhead stream comprising a higher concentration of acetaldehyde than the corresponding distillation feed stream; and contacting the second overhead stream with an acid catalyst to convert at least a portion of the acetaldehyde to an aldehyde derivative having a higher boiling point than acetaldehyde. Yet another aspect of the disclosure relates to an acetic acid production system, having: a reactor to react methanol and carbon monoxide in the presence of a carbonylation catalyst to form acetic acid; a flash vessel that receives a reaction mixture comprising the acetic acid from the reactor; a first distillation column that receives a vapor stream from the flash vessel; a decanter that receives a condensed overhead stream from the distillation column; a second distillation column that receives a portion of a heavy organic phase stream and/or a portion of a light aqueous ph