Abstract: Economical processes are disclosed for preparing relatively pure polycarboxylic acid from typical crude products of liquid phase oxidation, which do not involve intermediate steps of ester formation or require any alkanol containing solvent, for purification of "crude" polycarboxylic acid containing impurities which include one or more monofunctional aromatic compounds, trifunctional aromatic compounds, and/or color causing organic compounds formed by oxidation of a corresponding substituted aromatic compound in a liquid phase, e.g. 2,6-naphthalene dicarboxylic acid by liquid phase oxidation of 2,6-dimethyl naphthalene. The invention provides integrate processes which comprise reacting crude oxidation product with a polyalkyl amine amine, e.g. trialkylamine, forming an aqueous solution of the salts thus obtained, separating deleterious compounds from the solution, and recovering the polyalkyl amine and a relatively pure polycarboxylic acid product.

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 process for preparing purified dimethyl-2,6-naphthalenedicarboxylate by the esterification of 2,6-naphthalenedicarboxylic acid is disclosed and which process provides for the efficient removal of the mono methyl ester of 2,6-naphthalenedicarboxylic acid produced during the esterification reaction.

Abstract: Substantial proportions of methyl acetate and unreacted polymethylbenzene are recovered from the waste gas produced during the oxidation of a polymethylbenzene to its corresponding polycarboxylic acid by passing the waste gas, after being cooled for removal of water vapor, through at least one bed of activated carbon and subsequently desorbing the methyl acetate and polymethylbenzene from the bed by passing a desorbing medium, such as steam, through the bed. Preferably, the cooled stream is heated to a temperature of at least 21.degree. C. (70.degree. F.) prior to being passed into the bed of activated carbon.There is also disclosed an improved process for the oxidation of a polymethylbenzene to its corresponding aromatic polycarboxylic acid, which process comprises producing the polycarboxylic acid and waste gas comprising methyl acetate, water vapor, and unreacted polymethylbenzene and treating the waste gas according to the above method.

Abstract: A method and system for increasing conversion efficiency of aromatic alkyl reactant to aromatic carboxylic acid product and for improving the quality of the product, are disclosed. The method and system provide for the continuous production of an aromatic carboxylic acid by the liquid phase, exothermic oxidation of an aromatic alkyl in a vaporizable solvent in an oxidation reactor. The reactor makes use of a vented, overhead condenser system and a separator system for condensation of vaporized reactor material, separation of the condensed solvent therefrom, and reflux of separated solvent back into the reactor. The improvement comprises combining the reactor liquid feedstream with the refluxed solvent upstream from the oxidation reactor.

Abstract: Optical density of terephthalic acid is reduced in excess of ninety percent by the direct addition of water to selected crystallizers in a precipitative process based on hydrogenation and flask crystallization.

Abstract: The method and apparatus for manufacturing terephthalic acid (TA) are capable of producing TA having a closely controlled, desired amount of contaminant, 4-carboxy-benazldehyde (4-CBA), therein and/or a closely controlled optical density. In the method, a feed of para-xylene or similar feedstock mixed with catalyst components and solvent system is fed to a reactor stage comprising one or more reactors with oxygen for carrying out an exothermic oxidation reaction in the reactor stage, and an output slurry from the reactor stage is fed with oxygen to a first crystallizer of a crystallizing stage. The method comprises the steps of: determining empirical relationships between (1) the desired level of contaminant in the TA output product from the crystallizing stage and the oxygen uptake in the first crystallizer and (2) the oxygen uptake in the first crystallizer and the CO.sub.2 in the vent gas from the reactor stage; monitoring the CO.sub.

Abstract: A method is disclosed for the continuous production of an aromatic carboxylic acid by the liquid phase, exothermic oxidation of an alkyl aromatic in a solvent in an oxidation reactor employing an overhead condenser system for condensation and recycle of vaporized solvent to the reactor, wherein the oxidation is performed at a relatively reduced temperature or pressure or at a relatively increased throughput of the alkyl aromatic without exceeding the elevation head between the condenser system and the reactor.

Abstract: A process for the removal of para-toluic acid from purified terephthalic acid is disclosed. This process comprises extracting the para-toluic acid with paraxylene from the aqueous terephthalic acid-water phase and recycling the para-toluic acid and paraxylene to the paraxylene oxidation reactor. The process improves the overall yield of purified terephthalic acid recovered. Purified terephthalic acid is used as a basic raw material in the manufacture of polyester fibers and films.

Abstract: Acetic acid can be prepared in high conversions and selectively by the oxidation of liquid n-butane at temperatures of from 120.degree. C. up to 230.degree. C. in the presence of an acetic acid solution containing bromine ions in combination with ions of cobalt or cobalt and manganese. The debutanized effluent of such oxidation consists mainly of acetic acid and water but also contains esters and ketones boiling lower than acetic acid, some higher carbon content aliphatic acids and metal salts boiling higher than acetic acid and rather small amounts of 3-bromo-2-butanone which, although boiling higher than acetic acid, cannot be separated by simple distillation as can be the other non-acetic acid organic impurities. The present inventive technique for removal of said bromo-ketone has for its concept the use of a combination of cryogenic crystallization and removal of adhering mother liquor which can be practiced continuously in known apparatus devised for other fractional crystallizations.

Abstract: Excessive energy consumption of a combination of multi-fractionations and multi-distillations of concentrating aqueous acetic acid product of liquid phase oxidations, especially oxidation of liquid n-butane with oxygen gas while the butane is dissolved in liquid acetic acid containing a catalyst system comprising Co-Br or Co-Mn-Br, is avoided and an otherwise hard to remove bromo-ketone is readily removed by a combination of sequential steps of decompressing the oxidation reaction mixture to remove unreacted butane as well as gaseous products, heat treating the decompressed liquid at a temperature of from 150.degree. C. up to 200.degree. C. for from 15 up to 150 minutes, subjecting the heat treated liquid to fractionation while recycling to the rectification zone thereof an aqueous portion of low boiling impurities as a means for concentrating the acetic acid and thereafter further concentrating the acetic acid produced by continuous fractional crystallization.