Process for the production of acetic acid

US20060247466A1Active Publication Date: 2006-11-02CELANESE INT CORP
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  • Process for the production of acetic acid

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first embodiment

[0054] Further in accordance with this first embodiment of the present invention, second vapor phase stream 36 is extracted with water (generally indicated by 70) to remove and / or reduce PRC's, notably acetaldehyde. Acetaldehyde is extracted by the water to obtain aqueous acetaldehyde stream 72, which is PRC-rich, and in particular acetaldehyde-rich. Aqueous acetaldehyde stream 72 will generally be treated as a waste, although in some embodiments acetaldehyde may be stripped, with the water being recirculated to the process. The raffinate, notably containing methyl iodide is desirably returned to the carbonylation process by stream 74. The efficiency of the extraction will depend on such things as the number of extraction stages and the water to feed ratio.

[0055] Extraction with water 70, in accordance with this first or other embodiments of the present invention, can be either a singlestage or multistage extraction and any equipment used to conduct such extractions can be used in t...

second embodiment

[0057] In accordance with the present invention, also illustrated in FIG. 1, low-boiling overhead vapor stream 28 is condensed in decanter 16 where it is biphasically separated to form a condensed heavy liquid phase and a condensed light liquid phase 30. The condensed light liquid phase 30 is provided to distillation column 18 via stream 30 / 32. Again, in this and other embodiments of the present invention, a portion of stream 30 can be directed back to the light ends column 14 as reflux stream 34. In distillation column 18, a second vapor phase stream 36 overhead and a higher boiling liquid phase residuum stream 38 are formed. A sidestream 80, comprising methyl acetate, is also taken.

[0058] The sidestream 80 allows the distillation column 18 to be operated under conditions desirable for obtaining a higher concentration of acetaldehyde in second vapor phase stream 36 while providing a mechanism for removing methyl acetate that might otherwise build up in the center of distillation co...

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Abstract

A process for the reduction and / or removal of permanganate reducing compounds formed by the carbonylation of methanol in the presence of a Group VIII metal carbonylation catalyst to produce acetic acid is disclosed. More specifically, a process for reducing and / or removing permanganate reducing compounds or their precursors from intermediate streams during the formation of acetic acid by said carbonylation processes is disclosed. In particular, a process in which a low boiling overhead vapor stream from a light ends column is subjected to a single distillation to obtain an overhead that is subjected to an extraction to selectively remove and / or reduce PRC's from the process is disclosed.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] This invention relates to a process for the production of acetic acid and, in particular, to an improved process for the reduction and / or removal of permanganate reducing compounds formed by the carbonylation of methanol in the presence of a Group VIII metal carbonylation catalyst to produce acetic acid. More specifically, this invention relates to an improved process for reducing and / or removing permanganate reducing compounds or their precursors from intermediate streams during the formation of acetic acid by said carbonylation processes. [0003] 2. Technical Background [0004] Among currently employed processes for synthesizing acetic acid, one of the most useful commercially is the catalyzed carbonylation of methanol with carbon monoxide as taught in U.S. Pat. No. 3,769,329, issued to Paulik et al. on Oct. 30, 1973. The carbonylation catalyst contains rhodium, either dissolved or otherwise dispersed in a liquid re...

Claims

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Application Information

Patent Timeline
02 Nov 2006
Publication
US20060247466A1
IPC
C07C51/14; C07C45/90
CPC
C07C51/44; C07C51/48; C07C53/08; C07C51/12
Inventors
ZINOBILE, RAYMOND J.; SCATES, MARK O.