Amoco Corporation

Standard Oil Company (indiana)

Other

The Standard Oil Company

Hobe Schroeder

David A Palmer

Ricky L Wittman

George E Kuhlmann

Nicholas C Huie

Houssam M Naim

Sydney G Horsfield

Juergen K Holzhauer

David E James

Stephen J Pietsch

Rusins Albertins

Delbert H Meyer

Donald E Thomka

Stanley J Kulpa

Jeffrey H Schott

A method is disclosed for the purification of crude terephthalic acid, crude isophthalic acid or a crude naphthalene dicarboxylic acid that employs a titanium dioxide-supported purification catalyst.

Catalyst and method for purifying crude terephthalic acid, isophthalic

A method is disclosed for the purification of crude aromatic carboxylic acid by passing a solution of crude aromatic carboxylic acid in the presence of hydrogen through a first zone containing a hydrogenation catalyst based on a carbon carrier material then passing the solution through an abrasion resistant material thereby reducing the amount of carbon particles contained in the purified aromatic carboxylic acid.

Method for purifying crude aromatic carboxylic acids

Solutions of crude isophthalic acid are purified by hydrogenation to provide purified isophthalic acid having a predetermined color scale b*-value or optical density.

Purification of crude isophthalic acid

A method for purifying a naphthalene dicarboxylic acid produced by the liquid phase oxidation of a kialkylnaphthalene or partially oxidized derivative thereof in the presence of a catalyst comprising a bromine-containing component and at least one of a cobalt- or manganese-containing component.

Method for purifying a crude naphthalene dicarboxylic acid

Solutions of crude isophthalic acid are purified by hydrogenation in the presence of a catalyst comprising two Group VIII noble metal-containing components.

Aqueous solutions of crude terephthalic acid are purified by hydrogenation in the presence of plural noble metal catalysts in separate layers. Initially, the solution to be purified is passed through a layer of ruthenium-on-carbon catalyst, rhodium-on-carbon catalyst, or platinum-on-carbon catalyst, and thereafter through a layer of palladium-on-carbon catalyst. Optionally, the purified aqueous terephthalic acid solution can be treated further to decrease the 4-carboxybenzaldehyde content thereof by passing it through a layer of rhodium-on-carbon catalyst downstream from the palladium-on-carbon catalyst layer.

Purification of crude terephthalic acid

A process is disclosed for purifying a crude terephthalic acid mother liquor stream comprising oxidation catalysts, terephthalic acid, color bodies and impurities by hydrogenation in the presence of a rhodium-on-carbon catalyst wherein color bodies and impurities are hydrogenated to saturated compounds for subsequent oxidation to carbon oxides. The terephthalic acid in said stream is thereupon recovered.

Method for purifying terephthalic acid recycle streams

A method is disclosed for reactivating a Group VIII noble metal catalyst employed in the purification of crude terephthalic acid formed by the liquid-phase oxidation of p-xylene in the presence of a catalyst comprising cobalt, manganese and bromine components.

Method for reactivating a group VIII noble metal catalyst for use in the

Metallic catalysts are improved in performance and life when extended as a thin surface layer upon a porous, sintered metal substrate, particularly when employed in hydrogenation or decarbonylation reactions.

Catalyst composition

A particulate catalyst composition suitable for purification of terephthalic acid under reducing conditions and a method of preparation of such catalyst are disclosed. The catalyst composition includes catalytically active rhodium on a porous, granular, carbonaceous support material having a surface area of at least about 600 m.sup.2 /gram. Rhodium is present in an amount of about 0.01 to about 2 weight percent, based on the total weight of dry catalyst composition and calculated as elemental metal. In the presence of hydrogen, this catalyst exhibits a reduced terephthalic acid decomposition rate that is comparable to that for a palladium-on-carbon catalyst having the same catalyst metal loading. The catalyst is prepared by contacting a carbonaceous support material having a surface area of at least 600 m.sup.2 /gm and a pH value in its aqueous suspension of 9-11 with an aqueous rhodium salt solution having a pH of 1-4.

Rhodium on carbon catalyst

Aqueous solutions of crude terephthalic acid are purified to relatively low 4-carboxybenzaldehyde levels under hydrogenation conditions by using a layered catalyst bed. The aqueous terephthalic acid solution to be purified is first passed through a particulate primary catalyst layer constituted by palladium on active carbon and thereafter through a particulate secondary catalyst bed constituted by rhodium on active carbon.

Purification of terephthalic acid to relatively low levels of

The oxidation of butane vapor with air produces an impure maleic anhydride which when fractionated to first remove materials boiling lower than maleic anhydride and then a maleic anhydride product, leads to a maleic anhydride product fraction which when held at 140.degree. C. for 90 minutes discolors and is not a commercially acceptable product. Such discoloration can be substantially reduced by maintaining the impure maleic anhydride at a temperature from 60.degree. up to 200.degree. C. in the presence of small amounts of either hydrogen peroxide and/or sulfuric acid.

Aged molten color of maleic anhydride

Phthalic anhydride of commercially acceptable quality is recovered in high (94-96%) yields from a mixture containing, on a weight basis, from 70 to 90% o-phthalic acid, 1.5 to 21% water, 0.3 up to 13% benzoic acid, 0.2 up to 2% o-toluic acid, 0.2 to 1% 2-carboxybenzaldehyde, 0.1 up to 2% phthalide, from 1.3 up to 10% higher boiling materials, and from 0.05 up to 0.8% bromine by rapid dehydration of o-phthalic acid to its anhydride and rapid evaporation thereof followed by contact of the resulting vapor mixture with a noble metal catalyst to remove bromine and then with an inert reflux liquid in a fractionation zone to remove water and to provide a partial purification of the anhydride, removal of phthalide therefrom by only heating said partially purified anhydride in the presence of a catalytic amount of an alkali metal hydroxide having a molecular weight of at least 56 followed by fractionation of the phthalide-free mixture. Such process is more commercially attractive than melting said mixture containing 70 to 90% o-phthalic acid to dehydrate it to its anhydride and recovering the anhydride by fractionation because such apparently simple process cannot produce phthalic anhydride of a color or purity to be commercially acceptable nor can it provide an anhydride product substantially free of phthalide and bromine.

Formation, purification and recovery of phthalic anhydride

Undesirable discoloration of resultant phthalic anhydride and decomposition thereof and/or o-phthalic acid accompanying dehydration of o-phthalic acid to its anhydride in the presence of oxidation catalyst components Co, Mn and Br can be avoided by the rapid dehydration of o-phthalic acid and rapid vaporization of its anhydride occurring at a reduced pressure of downward from 760 mm Hg down to 40 mm Hg and at a temperature of from 180.degree. C. up to 250.degree. C. under continuous flow conditions which permit rapid removal of anhydride as vapor stream from catalyst components remaining as part of a fluid residue.

Phthalic anhydride formation and separation

Water is separated from a mixture of vapors containing 60 to 86 wt. % phthalic anhydride, 5 to 25 wt. % water, 0.8 to 10 wt. % benzoic acid, 0.1 to 4 wt. % o-toluic acid and up to 5 wt. % impurities boiling just above phthalic anhydride (PAN) by a fractionation zone whose reflux liquid is insert to PAN and the aromatic acids and immiscible with water but dissolves PAN at temperatures between its melting and freezing points and also dissolves benzoic acid and o-toluic acid at such temperatures. The reflux liquid or a component thereof when not a single compound leaves the top of the fractionation system as a vapor and does not leave the bottom thereof with PAN. Such water separation technique avoids having PAN vapors in a condenser whose cooled surfaces can and do become coated with solid PAN.

Growing community of inventors

Warrenville, IL, United States of America

Hobe Schroeder