Abstract: A method and apparatus for preparing purified terephthalic acid and, optionally, isophthalic acid from mixed xylenes. The method of the present invention purifies the oxidation reactor effluent containing a mixture of terephthalic acid and isophthalic acid as well as minor amounts of 4-carboxybenzaldehyde (4-CBA), 3-carboxybenzaldehyde (3-CBA), and toluic acid isomers, to produce purified terephthalic acid and, optionally, purified isophthalic acid in an integrated process.

Abstract: A method and apparatus for purifying crude terephthalic acid from a liquid dispersion thereof also containing impurities selected from unreacted starting materials, solvents, products of side reactions and/or other undesired materials is provided. The method comprises the steps of filtering the dispersion to form a crude terephthalic acid filter cake, dissolving the filter cake in a selective crystallization solvent at an elevated temperature to form a solution, crystallizing purified terephthalic acid from the solution in the crystallization solvent by reducing the pressure and temperature of the solution, and separating the crystallized purified terephthalic acid from the solution. According to the invention, the selective crystallization solvent is non-aqueous, non-corrosive and essentially non-reactive with terephthalic acid. Preferably, the selective crystallization solvent is N-methyl pyrrolidone.

Abstract: A method for reducing carboxybenzaldehyde isomers in crude terephthalic and/or isophthalic acids is described. Crude TPA or IPA is dissolved in N-methyl pyrrolidone and is subsequently contacted with an oxidant, such as substantially anhydrous hydrogen peroxide, to convert the carboxybenzaldehyde isomer (4-CBA or 3-CBA) to TPA or IPA under moderate temperature and pressure conditions.

Abstract: A process for the production of a trimellitic acid by oxidizing dialkyl aromatic aldehyde and/or its oxide derivative in a liquid phase, the oxidation being carried out in a lower aliphatic carboxylic acid solvent having a water content of 5 to 70% by weight in the presence of a catalyst containing a heavy metal and bromine or being carried out in a solvent containing a lower aliphatic carboxylic acid in the presence of a bromine-manganese catalyst system containing zirconium and/or cerium, and a process for the production of high-quality trimellitic acid anhydride from the trimellitic acid.

Abstract: The invention provides a method for purifying a crude naphthalenedicarboxylic acid comprising the steps of mixing a crude naphthalenedicarboxylic acid and a water/alcohol solvent to esterify a part of the naphthalenedicarboxylic acid, thereby dissolving a naphthalenedicarboxylic ester into the solvent, and then contacting the resulting reaction mixture with hydrogen in the presence of a hydrogenation catalyst to hydrogenate impurities which are contained in the crude naphthalenedicarboxylic acid and which are capable of being hydrogenated, thereby dissolving and removing hydrogenation products into the water/alcohol solvent. A mixture of a naphthalene dicarboxylic acid and a naphthalenedicarboxylic ester with reduced impurity contents, or a high-purity naphthalenedicarboxylic acid can be obtained.

Abstract: A process for producing a high-purity naphthalenedicarboxylic acid having an improved hue or an excellent hue from a crude naphthalenedicarboxylic acid obtained by the oxidation of dialkyl naphthalene, industrially advantageously at high yields, which comprises dissolving a crude naphthalenedicarboxylic acid obtained by the oxidation of dialkyl naphthalene in an aqueous solution containing an aliphatic amine, an alicyclic amine or acetonitrile, removing heavy metal components contained as impurities until the content of the heavy metal components based on the crude naphthalenedicarboxylic acid is 100 ppm or less, and heating the aqueous solution containing a naphthalenedicarboxylic acid amine salt to distill off the amine.

Abstract: Disclosed is a process for the purification of a naphthalenedicarboxylic acid (NDA) which has been manufactured by the oxidation of a dialkylnaphthalene in the presence of a molecular oxygen-containing gas and a heavy metal-containing catalyst and contains metal residues, e.g., cobalt and manganese residues, as impurities. The process involves contacting an acetic acid slurry of a NDA, typically 2,6-naphthalenedicarboxylic acid, containing such metals, with acetic anhydride.

Abstract: A method and apparatus for purifying crude terephthalic acid from a liquid dispersion thereof also containing impurities selected from unreacted starting materials, solvents, products of side reactions and/or other undesired materials is provided. The method comprises the steps of filtering the dispersion to form a crude terephthalic acid filter cake, dissolving the filter cake in a selective crystallization solvent at an elevated temperature to form a solution, crystallizing purified terephthalic acid from the solution in the crystallization solvent by reducing the temperature of the solution, and separating the crystallized purified terephthalic acid from the solution. According to the invention, the selective crystallization solvent is non-aqueous, non-corrosive and essentially non-reactive with terephthalic acid. Preferably, the selective crystallization solvent is N-methyl pyrrolidone.

Abstract: A process for preparing purified 2,6-naphthalenedicarboxylic acid which comprises hydrolyzing a dialkyl-2,6-naphthalenedicarboxylate with water at a reaction temperature of at least about 450.degree. F. under liquid phase condition, the amount of water present being sufficient to solubilize, at the reaction temperature, at least about 10 percent of the 2,6-naphthalenedicarboxylic acid formed; and a process for purifying 2,6-naphthalenedicarboxylic acid comprising combining impure 2,6-naphthalenedicarboxylic acid with a purification solvent, heating the resulting mixture under liquid phase conditions at a temperature of at least about 500.degree. F. to form a product mixture and thereafter recovering from the product mixture purified 2,6-naphthalenedicarboxylic acid.

Abstract: There is provided a method of purifying a crude aromatic dicarboxylic acid which comprises purifying an aqueous solution of an organic amine salt of the crude aromatic dicarboxylic acid, and then thermally decomposing the organic amine salt whereby to recover the thus highly purified aromatic dicarboxylic acid.

Abstract: A process for preparing purified 2,6-naphthalenedicarboxylic acid which comprises hydrolyzing a dialkyl-2,6-naphthalenedicarboxylate with water at a reaction temperature of at least about 450.degree. F. under liquid phase condition, the amount of water present being sufficient to solubilize, at the reaction temperature, at least about 10 percent of the 2,6-naphthalenedicarboxylic acid formed; and a process for purifying 2,6-naphthalenedicarboxylic acid comprising combining impure 2,6-naphthalenedicarboxylic acid with a purification solvent, heating the resulting mixture under liquid phase conditions at a temperature of at least about 500.degree. F. to form a product mixture and thereafter recovering from the product mixture purified 2,6-naphthalenedicarboxylic acid.

Abstract: An improved method for recovery of alkali metal or alkaline-earth metal terephthalate and of alkylene glycol, from polyalkylene terephthalate, in particular from polyethylene terephthalate (P.E.T.), alkylene glycol, in particular ethylene glycol produced in the form of vapor during the saponification reaction, initiated by the action of intensive kneading of polyalkylene terephthalate and the alkaline reagent at a temperature of 100.degree. to 200.degree. C. The alkylene glycol is recovered in gaseous form by entrainment by an inert gas or by extraction under low pressure. The alkaline terephthalate or alkaline-earth terephthalate is obtained in solid or powder form; it can easily be stored, transported and redissolved, in order to be purified and possibly transformed into terephthalic acid or ester.

Abstract: A terephthalic acid slurry in acetic acid is produced by oxidizing p-xylene in acetic acid, removing water by evaporation of a stream of water and acetic acid, and returning acetic acid to the oxidation step. The terephthalic acid is separated from the reaction medium in a first zone to leave a deposit on a band, the deposit is washed with a first aqueous medium in a second zone, removed from the band in a third zone, and admixed with a second aqueous medium. Reaction medium is passed from the first zone to the oxidation step and terephthalic acid is recovered, preferably after further purification.

Abstract: A process for recovering monomer from multi-component waste material that includes a hydrolyzable polymer, the process including contacting the multi-component waste material with water and subjecting the resulting mixture to heat and pressure to form a liquid aqueous portion which mainly includes depolymerization products of the hydrolyzable polymer and a water insoluble portion which mainly includes components other than the depolymerization products; separating the liquid aqueous portion and the water insoluble portion; subjecting the separated aqueous portion to a pressure that is lower than that of step (a) and heat to produce a residue and a distillate which contains monomer; and separating the monomer in the distillate from other components in the distillate. The process is particularly useful for recovering caprolactam from waste materials that include nylon 6.

Abstract: Caprolactam is obtained from mixtures which contain polymers or thermoplastic molding materials having the repeating unit--N(H)--(CH.sub.2).sub.5 --C(O)--(a) by cleavage at elevated temperatures in the presence of a base under reduced pressure or (b) in the presence of water, by using a mixture essentially comprisingfrom 50 to 99.9% by weight of a polymer or of a thermoplastic molding material having the repeating unit--N(H)--(CH.sub.2).sub.5 --C(O)--from 0.1 to 50% by weight of additives selected from the group consisting of inorganic fillers, organic and inorganic pigments and dyes,from 0 to 10% by weight of organic and/or inorganic additives,from 0 to 40% by weight of non-polyamide-containing polymers andfrom 0 to 20% by weight of polyamides, with the exception of polycaprolactam and copolyamides prepared from caprolactam,and carrying out the cleavage in the presence of a base under reduced pressure, the water content of the mixture used being not more than 0.

Abstract: A process for the production of terephthalic acid comprises subjecting polyalkylene terephthalate to hydrolysis using a ratio of water to polyalkylene terephthalate in the mixture prior to heating and carrying out the reaction under conditions such that, at the reaction temperature, a significant proportion of the terephthalic acid produced is in the solid phase. The degree of recrystallization necessary to recover the terephthalic acid produced is thereby reduced. The reaction can with advantage be carried out with alkylene glycol present in the mixture prior to hydrolysis.

Abstract: Processes are disclosed for recovery and purification of dibasic aromatic acids from waste polyester film, fiber, bottles, manufacturing residues, and other manufactured articles. The processes comprises: depolymerizing polyester resin in a solvent under conditions suitable for hydrolysis of ester bonds to obtain a mixture containing a solution of aromatic acid and impurities consisting of alcohol and/or other components of the resin; burning impurities in a liquid-phase oxidation with an oxygen-containing gas in the presence of an oxidation catalyst at elevated pressures and temperatures, to obtain an oxidation product containing the desired aromatic acid; and crystallizing and separating from the oxidation system a resulting crude dibasic aromatic acid.

Abstract: 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.

Abstract: Provided is a facile three step process for preparing 2-phenylterephthalic acid starting with p-xylene, followed by alkylation, dehydrogenation, and oxidation of the methyl groups corresponding to the origional p-xylene. The product, 2-phenylterephthalic acid, is useful as an intermediate in the synthesis of polyesters comprised of residues of 2-phenylterephthalic acid.

Abstract: Disclosed herein is a process for producing highly purified benzenedicarboxylic acid isomers without an additional catalytic reductive purification step, which comprises (a) an oxidation step wherein xylene isomer is oxidized with molecular oxygen or molecular oxygen containing gas in the presence of a catalyst system composed of cobalt, manganese, bromine and at least one selected from nickel, chromium, zirconium and cerium in lower aliphatic carboxylic acid; and (b) an extraction/post-oxidation step wherein the oxidation product is crystallized to give cake of crude benzenedicarboxylic acid isomer, the cake is reslurried by adding lower aliphatic carboxylic acid solvent thereto followed by heating in order to extract impurities contained therein into the solvent, and the resulting slurry is oxidized with said catalyst system at a temperature of 2.degree.-80.degree. C.

Abstract: 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.

Abstract: Terephthalic acid is produced by oxidation of para xylene, purified in an aqueous phase and recovered by precipitating a purified product from the aqueous phase, the aqueous phase mother liquor is then cooled or evaporated to produce a further less pure precipitate and a second mother liquor and the less pure precipitate is returned to the reaction medium and/or the water of the second mother liquor is used to dissolve the crude solid and/or the second mother liquor is treated to recover water which is used to wash the precipitate recovered from the aqueous solution. The process produces better yields of terephthalic acid, reduces the use of water and reduces problems in the disposal of polluted waste water.

Abstract: Disclosed is a method for preparing an aromatic carboxylic acid comprising oxidizing in the liquid phase an aromatic feed compound containing at least one alkyl or acyl group with a molecular oxygen-containing gas, in a solvent comprising a low molecular weight aliphatic carboxylic acid, and in the presence of a heavy metal oxidation catalyst, thereby forming an oxidation reaction product mixture comprising an aromatic carboxylic acid; subsequently heating the oxidation reaction product mixture at a temperature of at least about 500.degree. F. to form a second product mixture; and recovering from the second product mixture the aromatic carboxylic acid. The method of this invention provides for purer, larger particle size aromatic carboxylic acid product.

Abstract: A high purity naphthalene dicarboxylic acid (NDCA) is easily and rapidly produced by reacting a dialkylester of NDCA within a temperature range of 70.degree.-350.degree. C.

Abstract: A method for purifying a naphthalenedicarboxylic acid comprising contacting an impure naphthalenedicarboxylic acid with hydrogen in the presence of a hydrogenation catalyst and a solvent comprising a low molecular weight carboxylic acid, at a temperature of at least about 500.degree. F., and a pressure sufficient to maintain the solvent at least partially in the liquid phase and thereafter recovering purified naphthalenedicarboxylic acid.

Abstract: A process for purifying a crude terephthalic acid obtained by neutralization of the disodium terephthalate from alkali waste water from a polyester fabric-treatment process, into polymer grade terephthalic acid. The crude terephthalic acid is crushed, and fed to the kiln at 150.degree.-300.degree. C. for thermal treatment in an aqueous solution. The ammoniated, and the impurities in the solution are removed by adsorption followed by deammoniation, which may be accomplished by heating or by treatment with sulfuric acid.

Abstract: A process is disclosed for counter-current positive displacement of an aliphatic carboxylic acid of 1 to 5 carbon atoms from a filter cake of an aromatic polycarboxylic acid containing the aliphatic carboxylic acid wherein mother liquor retained by the aromatic polycarboxylic acid has a concentration of the aliphatic carboxylic acid of 5000 ppmw, or less, based upon weight of the aromatic polycarboxylic acid present. This method is useful for the manufacture of crude terephthalic acid which is used after purification for the preparation of polyesters used for the manufacture of fabrics, fibers and plastic bottles.

Abstract: A process for producing highly pure isophthalic acid which comprises (a) carrying out liquid phase oxidation of an m-dialkyl benzene with molecular oxygen in an acetic acid solvent in the presence of a heavy metal catalyst to form crude isophthalic acid, (b) contact-treating the resulting crude isophthalic acid with a noble metal catalyst belonging to the Group VIII of the Periodic Table supported by activated carbon in the presence of hydrogen, and then (c) separating the deposited isophthalic acid crystal and (d) filtration-treating the separated mother liquor and (e) recirculating the mother liquor thus treated into the liquid phase oxidation step (a) for reusing as a solvent in step (a) is disclosed.

Abstract: Provided is a continuous process for producing 2,6-naphthalenedicarboxylic acid by the liquid phase oxidation of 2,6-dimethylnaphthalene comprising continuously adding to a reaction zone the oxidation reaction components comprising 2,6-dimethylnaphthalene, a source of molecular oxygen, a solvent comprising an aliphatic monocarboxylic acid, and a catalyst comprising cobalt, manganese and bromine components, wherein the atom ratio of manganese to cobalt is about 5:1 to about 0.3:1, the total of cobalt and manganese is at least about 0.40 weight percent based on the weight of solvent, and maintaining the contents of the reaction zone at a temperature of about 370.degree. F. to about 420.degree. F. and at a pressure sufficient to maintain at least a portion of the monocarboxylic acid in the liquid phase thereby oxidizing the 2,6-dimethylnaphthalene to 2,6-naphthalenedicarboxylic acid.

Abstract: In a process for producing purified terephthalic acid which comprises catalytically oxidizing p-xylene in liquid phase to produce crude terephthalic acid containing 4-carboxybenzaldehyde as a main impurity therein, and treating the crude terephthalic acid with hydrogen in the presence of hydrogenation catalyst in a reaction vessel, thereby to produce purified terephthalic acid containing 4-carboxybenzaldehyde in an amount of fixed range in a stationary manner, there is provided an improvement which makes it possible for the treatment to reach the stationary state promptly after partial exchange of deactivated catalyst for a new one. The improvement comprises feeding into the reactor crude terephthalic acid which contains 4-carboxybenzaldehyde in an amount larger than that in the stationary state of the treatment, and treating the terephthalic acid until the treatment reaches the stationay state.

Abstract: A process for preparing 2,6-naphthalenedicarboxylic acid comprising oxidation reaction of 2,6-diisopropylnaphthalene or an oxidation product thereof with molecular oxygen in a solvent containing an aliphatic carboxylic acid in the presence of a catalyst comprising cobalt and manganese as heavy metals and a bromine compound is disclosed, in which said oxidation reaction is carried out in the presence of at least one nitrogen-containing compound selected from the group consisting of a pyridine compound, ammonia, a carboxylic acid ammonium salt, urea, a urea derivative, an amine, and a carboxylic acid amide. 2,6-Naphthalenedicarboxylic acid can be obtained at higher purity and in increased yield.

Abstract: A process for purifying crude 2,6-naphthalene dimethyl dicarboxylate (hereinunder referred to as 2,6-NDM) which comprises dissolving the crude 2,6-NDM into a C.sub.6 -C.sub.9 aromatic hydrocarbon, then contacting the solution of 2,6-NDM and the hydrocarbon with an hydrotalcite-like laminar crystalline compound and activated carbon, then carrying out thermal filtration of the solution, and then cooling the solution to separate 2,6-NDM crystal from the solution is disclosed.

Abstract: A process for the production of high purity terephthalic acid, by subjecting a crude terephthalic acid product, resulting from the oxidation of a paradialkylbenzene and containing a 4-carboxybenzaldehyde and other impurities at a relatively high level, to an efficient purification with high yield of terephthalic acid. This process comprises subjecting a high temperature aqueous solution of the crude terephthalic acid product to (A) an oxidation treatment with an oxygen-containing gas while feeding oxygen at a feed rate in the range of 0.4-10 moles per mole of the 4-carboxylbenzaldehyde contained in the crude terephthalic acid and then to (B) a treatment with hydrogen.

Abstract: The invention is an improved method of purification of isophthalic acid comprising recycling a portion of the mother liquor solution into the feed solution of an isophthalic acid purification process. The improved method comprises the following steps:(a) dissolving crude isophthalic acid in a feed solution comprising a polar solvent at a temperature of from about 100.degree. C. to about 300.degree. C.;(b) crystallizing the isophthalic acid by cooling the solution of step (a) to a temperature of from about 35.degree. C. to about 120.degree. C.;(c) separating the isophthalic acid crystals from the solution and drying the crystals; and(d) recycling a portion of the solution remaining after the separation of isophthalic acid crystals back to the feed solution.

Abstract: Aromatic dicarboxylic acids, specifically 4,4'-dicarboxydiphenyl ether, terephthalic acid, 4,4'-carboxybis(benzoic acid) and the like, are purified by dissolving the crude acid in a monocarboxylic acid anhydride, purifying the resulting solution, and recovering a purified acid product therefrom.

Abstract: A process for dimerizing an aromatic halogen compound is disclosed, which comprises the step of: subjecting an aromatic halogen compound having at least one halogen atom bonded to an aromatic nucleus carbon to a dehalogenation-dimerization reaction in the presence of a catalyst, water, a reducing agent, and a halogen acceptor, the catalyst comprising a carrier supported thereon palladium and iron.

Abstract: A process is disclosed for producing fiber-grade terephthalic acid from waste polyethylene terephthalate film, fiber, bottles, manufacturing residues, and other manufactured articles. The process comprises depolymerizing waste polyethylene terephthalate in an aqueous mixture to obtain crude terephthalic acid having a b*-value less than 10.00 and an RFCVIS value of about 5000, or greater, which is thereupon hydrogenated in aqueous solution for a period of up to 8 hours. Organic and inorganic impurities are retained in the aqueous components. The purified terephthalic acid has a b*-value less than 2.00, a relative fluorescence concentration in visible light (RFCVIS) of less than 2500, metals content less than 100 ppmw and total organic impurities of less than 1000 ppmw.

Abstract: There are provided compounds of the formula: ##STR1## wherein R.sub.1 is a hydrogen or C.sub.1 -C.sub.5 alkyl; R.sub.2 is an C.sub.1 -C.sub.10 alkyl, aryl, aralkyl, or pyridyl, where the aryl, aralkyl, or pyridyl are unsubstituted or are substituted by C.sub.1 -C.sub.5 alkyl, C.sub.1 -C.sub.5 alkoxy, nitro, hydroxy, carboxy, amino, C.sub.1 -C.sub.5 alkylamino, C.sub.1 -C.sub.5 dialkylamino whose two alkyl groups may be different from each other, C.sub.2 -C.sub.3 alkanoylamino, or halogen and X is an C.sub.1 -C.sub.7 alkylene, C.sub.2 -C.sub.7 alkenylene, --CH(F)CH.dbd.CH(CH.sub.2).sub.3 --, --(CH.sub.2).sub.3 --S--(CH.sub.2).sub.2 --, --CH.sub.2).sub.2 --S--(CH.sub.2).sub.3 --, --C.sub.6 H.sub.4 --O--CH.sub.2 --or --CH.sub.2 CH.dbd.CH--m--C.sub.6 H.sub.4 --, or their pharmaceutically acceptable salts. The compounds are useful as antithrombotic, anti-vasoconstricting and anti-bronchoconstricting drugs.

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

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

Abstract: 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.

Abstract: An improved method for the preparation of a naphthalene dicarboxylic acid by liquid-phase catalytic oxidation of a diisopropylnaphthalene in a lower fatty acid-based solvent is disclosed wherein a catalyst system comprising bromine and the heavy metals cerium, cobalt, and manganese is used. The cerium compound used as a cerium source for the catalyst can be recovered from crystals of the naphthalene dicarboxylic acid product by dissolving the crystals in an alkali solution and separating the cerium compound as insolubles from the solution.

Abstract: 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.

Abstract: The present invention provides a process of preparing terephthalic acid of high quality which is characterized by:oxidizing p-xylene with molecular oxygen in an acetic acid solvent in the presence of a catalyst comprised of at least one heavy metal and bromine at a temperature of from 180.degree. to 230.degree. C. to convert at least 95 wt % of the p-xylene into terephthalic acid and, optionally, subjecting the resultant reaction mixture to low temperature post-oxidation with molecular oxygen at temperatures lower than the temperature of the first oxidation reaction, thereby obtaining a slurry containing terephthalic acid particles whose spectral reflectance defined below is not less than 70% and whose reflectance ratio (400/500) defined below is not less than 0.92;subjecting the slurry to high temperature post-oxidation with molecular oxygen at a temperature of from 235.degree. to 290.degree. C. and then to crystallization; andcollecting the resultant terephthalic acid from the reaction mixture.

Abstract: A method is disclosed for producing purified 5-t-butylisophthalic acid by the liquid-phase oxidation of 5-t-butyl-m-xylene in a solvent and in the presence of a catalyst comprising cobalt, manganese and bromine components.

Abstract: 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.

Abstract: Disclosed herein is a process for producing a highly pure produce of 2,6-naphthalenedicarboxylic acid in a large quantity at a moderate price by oxidizing 2,6-diisopropylnaphthalene while using a water-soluble salt of cobalt, a water-soluble salt of maganese or a mixture thereof, a water-soluble salt of cerium and a bromine compound as the catalyst of the oxidation.

Abstract: A catalyst, a process for preparing said catalyst, and a process for producing purified terephthalic acid, wherein 4-carboxybenzaldehyde is reduced to very low levels, wherein said catalyst is prepared by contacting a solution of a suitable palladium salt in an organic solvent with a suitable activated carbon support, wherein said palladium salt is reduced to palladium metal crystallites by said activated carbon support. Purified terephthalic acid is prepared by hydrogenating crude terephthalic acid in the presence of said catalyst.

Abstract: A process for producing fiber grade terephthalic acid is disclosed. In this process impurities having high molecular weight are eliminated by hydrogenation comprising the following steps: (a) treating an aqueous solution containing at least about 1 percent of said impure terephthalic acid with hydrogen at a temperature in the range of about 300.degree. F. to about 450.degree. F. and at a pressure sufficient to maintain the solution in the liquid phase in the presence of a supported or unsupported metallic Group VIII noble metal catalyst wherein both the metal and support components are insoluble in the solution at the temperature and at a hydrogen partial pressure of from about 30 to about 300 pounds per square inch; (b) separating the treated solution from the catalyst; (c) crystallizing terephthalic acid from the separated solution while retaining impurities and the reduced aromatic compounds dissolved in the resulting mother liquor at a temperature in the range of about 100.degree. F. to about 450.degree.

Abstract: Terephthalic acid is produced by oxidation of para xylene, purified in an aqueous phase and recovered by precipitating a purified product from the aqueous phase, the aqueous phase mother liquor is then cooled or evaporated to produce a further less pure precipitate and a second mother liquor and the less pure precipitate is returned to the reaction medium and/or the water of the second mother liquor is used to dissolve the crude solid and/or the second mother liquor is treated to recover water which is used to wash the precipitate recovered from the aqueous solution. The process produces better yields of terephthalic acid, reduces the use of water and reduces problems in the disposal of polluted waste water.