Celanese International Corporation

Hoechst Celanese Corporation

Madan Singh

Mark O Scates

G Paull Torrence

George A Blay

Michael L Karnilaw

Melchior A Meilchen

Wayne David Picard

Robin Suzanne Tanke

R Jay Warner

Jerry A Broussard

Edward F Dougherty

Hung-Cheun Cheung

Charles C Hobbs, Jr

Michael E Huckman

Valerie Santillan

Leon B Levy

Richard F Vogel, Jr

Peggy McKarns Macatangay

Stephen Andrew Houliston

Jerome F Perez

A method and system is provided for producing acetic acid by the catalytic carbonylation of methanol with carbon monoxide to obtain a reaction product stream comprising acetic acid and a minor amount of acetaldehyde. The acetaldehyde content in the reaction product stream is reduced by oxidation to convert at least a portion of the acetaldehyde in the stream to acetic acid or further to CO and H O. The oxidized stream may then be directed to the purification section, the reaction section, or both whereby the deleterious effects of acetaldehyde are reduced. Advantage of the present invention over conventional processes is the reduced need to dispose of acetaldehyde as waste and improved overall system efficiency in the production of acetic acid.

Oxidation treatment of a recycle stream in production of acetic acid by methanol carbonylation

Removal or reduction of permanganate reducing compounds and alkyl iodides from a carbonylation process stream

A process for inhibiting free-radical polymerization of an alpha,beta-unsaturated (&agr;,&bgr;-unsaturated) carboxylic acid, and for providing desired grade &agr;,&bgr;-unsaturated carboxylic acid for use following storage and transport is described herein. In particular, bulk storage and shipment such as with overseas transport is described. The process comprises combining the &agr;,&bgr;-unsaturated carboxylic acid with a phenolic inhibitor and a coinhibitor to form an inhibited mixture, storing the inhibited mixture, transporting the inhibited mixture, and removing the coinhibitor to provide the desired grade &agr;,&bgr;-unsaturated carboxylic acid for use. In preferred embodiments, the &agr;,&bgr;-unsaturated carboxylic acid is acrylic acid, the phenolic inhibitor is p-methoxyphenol, the coinhibitor is manganese cation, and removal of the coinhibitor is carried out using an ion exchange resin.

Stabilization and transport of &agr;, &bgr;-unsaturated carboxylic acid and removal of stabilizer

Disclosed is a method to manufacture high purity acetic acid. Although described in relation to that produced by a low water carbonylation process the present invention is applicable to other mechanisms for production of acetic acid which results in formation of permanganate reducing compounds such as acetaldehyde, propionic acid, and alkyl iodide impurities in intermediate process streams. It has been found that permanganate reducing compounds and alkyl iodides may be conveniently removed from a light phase of an intermediate stream in the reaction process by employing a multiple distillation process coupled with an optional extraction of acetaldehyde. The distillation process involves first distilling a light phase to concentrate the permanganate reducing compounds, and in particular the acetaldehyde, and then separating the permanganate reducing compounds and alkyl iodides in a second distillation tower. The second distillation serves to remove the permanganate reducing compounds and alkyl iodides from methyl iodide, methyl acetate, and methanol mixture. As an optional third step, the twice distilled stream may be directed to an extractor to remove any remaining quantities of methyl iodide from the aqueous acetaldehyde stream to obtain acetic acid as a final product in greater than 99% purity. It has been found that this process removes at least 50% of the permanganate reducing compounds and alkyl iodides and at least 20% of the propionic acid impurity from the intermediate light phase stream, and results in lower alkyl iodide concentration in the carbonylation reaction process, and in particular in the carbonylation reactor. It has also been found that during shut down of the inventive process, polymers of acetaldehyde tend to form in the base of the second distillation tower. To avoid or minimize the formation of these polymers, a constant flow of solvent is passed through the base of the column.

Removal of permanganate reducing compounds and alkyl iodides from a

A method is provided to improve the quality of recycle of certain residues by modifying the separation of alkanes and alkane-like materials and carbonyl-containing impurities from the recycle during the manufacture of acetic acid by the carbonylation of methanol. The improvement comprises operating a prior art stripper column in a reflux manner and partitioning the residue therefrom by the addition of water. The method also reduces the volume of disposal of potentially valuable recyclable reactants.

Removal of carbonyl impurities from a carbonylation process stream

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Corpus Christi, TX, United States of America

Madan Singh