Abstract: Improved mixing performance with reduced power input is obtained in an agitated oxidation reactor for converting an aromatic alkyl to the corresponding aromatic carboxylic acid by decreasing the clearance between the lowermost impeller element and the reactor bottom and by providing a flat blade turbine as the upper impeller element.

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 is disclosed for preparation of purified terephthalic acid containing 200 ppmw or less of p-toluic acid. A filter cake of purified terephthalic acid is prepared by filtering, under a differential pressure of about or greater than 0.5 psi over the system pressure and a temperature within the range of from about 100.degree. C. to about 205.degree. C., an aqueous slurry of purified terephthalic acid containing a solution of p-toluic acid. The aqueous solution of p-toluic acid remaining in the filter cake of purified terephthalic acid is displaced from the filter cake by water under a pressure gradient over the system pressure at a temperature within the range of from about 100.degree. C. to about 205.degree. C. Pressure flash evaporation of water remaining in the filter cake occurs upon release of the system pressure to lower pressure with consequent lower temperature. The crystalline terephthalic acid product containing 200 ppmw or less p-toluic acid can be dried under atmospheric pressure.

Abstract: A process is disclosed for the preparation of aliphatic monocarboxylic acids from primary aliphatic alcohols having 2 to 6 carbon atoms wherein the reaction is in semi-continuous or continuous mode. Acetic acid is prepared from ethanol in high conversion, selectivity and yield. Acetic acid is useful as a solvent for the manufacture of terephthalic acid and other organic compounds.

Abstract: There is provided a method for purifying an organic polycarboxylic acid wherein the amounts of organic monofunctional impurities associated therewith are substantially reduced, which method comprises conducting steam distillation of a stream comprising said polycarboxylic acid. In one embodiment of the method, a reactor effluent comprising a polycarboxylic acid is introduced into a crystallization zone, said effluent being subjected to crystallization and steam distillation coextensively in said crystallization zone.The method of the present invention may be used suitably to purify 1,4-cyclohexanedicarboxylic acid in a reactor effluent from the hydrogenation of a terephthalic acid by reducing the amounts of 4-methyl-1-cyclohexanecarboxylic acid and cyclohexanecarboxylic acid, as well as other organic impurities, contaminating the dicarboxylic acid.There is also provided the polycarboxylic acid purified by the method of the present invention.

Abstract: There is provided a clamp-type apparatus for connecting a first object, such as a vibratory mechanism, to a second object that is a box-type vessel having at least one slot in a side near a corner, such as a steamship truck container, which apparatus comprises: (a) a first plate having a first aperture and at least one second aperture, the at least one second aperture being used to attach the first object to the first side of the first plate; (b) a bolt-type fastener for attaching the second object to the second side of the first plate, the fastener passing through the first aperture and being capable of rotating about its axis; (c) a rod for rotating the fastener about its axis; and (d) a small second plate for preventing movement of the apparatus relative to the second object, the second plate being perpendicular to and attached to the first plate. There are also provided a method for connecting a vibratory mechanism to a steamship truck container and a method for vibrating a steamship truck container.

Abstract: A process for the production of trimellitic anhydride with improved color is disclosed. The process comprises heat treating trimellitic anhydride in the presence of oxides of boron or hydrated oxides of boron followed by fractionation. Trimellitic anhydride is used in the manufacture of polyesters and polyamide-imides.

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 continuous process is disclosed for the production of maleic anhydride by the partial oxidation of a hydrocarbon feedstock comprising n-butane in a concentration of at least 1.6 mole percent wherein a mixture of the feedstock and an oxidizing medium is contacted with a vanadium-phosphorus-oxygen catalyst wherein a solution of water and an alkyl ester of orthophosphoric acid is continually added to said feedstock, wherein ratio of water to elemental phosphorus in said alkyl ester is in the range of from about 6500:1 wt. to about 50,000:1 wt., water to phosphorus, and the differences in reaction temperature throughout the entire reaction zone is less than about 45.degree. C. (80.degree. F.).

Abstract: The addition of hafnium to oxidation catalysts provided by a heavy transition metal-bromine ion catalyst combination containing cobalt-manganese-bromine or manganese-bromine or cobalt-bromine and a soluble source of hafnium uniquely increases catalytic activity of the said catalyst combination for converting methyl groups on the benzene nucleus. The presence of hafnium in the total reactor contents is equal to or less than 250 parts per million by weight of the total reactor mother liquor. The solubility of the hafnium in the reactor solvent is such that reactor product cake contains less than 0.3 ppm by weight. Bromine emissions can be reduced.

Abstract: There is provided a process for recovering acetic acid from methyl acetate wherein the methyl acetate is hydrolyzed catalytically to methanol and acetic acid in the same tower or column that is used to separate the methanol from the acetic acid and the hydrolysis and separation are carried out coextensively in the vessel. The process is employed suitably in a process for the partial oxidation of a polymethylbenzene to a polycarboxylic acid in the presence of an oxidation catalyst and an acetic acid solvent.

Abstract: A continuous stirred-tank reactor suitable for the liquid-phase oxidation of an aromatic alkyl to an aromatic carboxylic acid is provided with vertically disposed, relatively narrow baffles on the reactor wall and with oxidizing gas inlet means below the agitator in the reactor. The baffle width is about 0.02 to about 0.04 times the diameter of the reactor.

Abstract: A process is disclosed for preparation of anhydrides containing additional carboxylic acid moieties and dianhydrides of disubstituted maleic anhydride compounds wherein the acid anhydrides and dianhydrides retain their alkene character. The resulting alkene compounds are useful as precursors for polyesters, thermally stable polyamide-imides and polyimides which are also disclosed, as well as a process for their preparation.

Abstract: A process is disclosed for oxidation of pseudocumene to trimellitic acid wherein process residue and bottoms from stripping procedures to recover process solvent are recycled and incorporated in filtrate mother liquor and reinjected into the oxidation reactor at a point in time at least after the first methyl group in the pseudocumene molecule has been oxidized to a carboxy group. Recovery of trimellitic acid is increased, catalyst recovery is increased in a form suitable for immediate recycle to the oxidation reaction, and waste products from the oxidation process are substantially reduced.

Abstract: A catalyst comprising a phosphorus-vanadium mixed oxide and existing in the form of geometric shapes, such as tablets, provides minimum expansion of the geometric shapes under process reaction conditions, since the catalyst in the form of said geometric shapes has been heated in an inert atmosphere at a temperature within the range of about 343.degree. C. (650.degree. F.) to about 704.degree. C. (1,300.degree. F.) prior to being exposed to an oxygen-containing atmosphere at an elevated temperature. This catalyst is suitable for the oxidation of a hydrocarbon, such as benzene or n-butane, to maleic anhydride.

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: A process for oxidizing a dialkyl substituted benzene, such as meta-xylene, to an aromatic polycarboxylic acid, such as isophthalic acid, in the presence of a solvent, such as acetic acid, in an oxidation zone followed by an oxidation-crystallization zone, wherein a secondary dehydration tower is used to separate water from the solvent in the overhead stream from the oxidation-crystallization zone and provide a solvent-rich fluid for recycle to the oxidation zone, resulting in expanded capacity of the process coupled with a minimization of captial cost.

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: An improved process is disclosed for preparation of silicon-containing aromatic polyacids by liquid phase oxidation of a silyl compound in the presence of oxygen and a catalyst comprising cobalt-manganese-bromine. 2-Trimethylsilyl-p-xylene is oxidized to 2-trimethylsilyl-terephthalic acid; 5-trimethylsilyl-m-xylene is oxidized to 5-trimethylsilyl-isophthalic acid, 2,5-bis (trimethylsilyl)-p-xylene is oxidized to 2,5-bis (trimethylsilyl)-terephthalic acid; 5-trimethylsilyl-pseudocumene is oxidized to 1,2,4-tricarboxy-5-trimethylsilyl benzene; and 1,3-bis-(p-tolyl)-tetramethyl-disiloxane is oxidized to 1,3-bis(p-carboxyphenyl)-tetramethyl-disiloxane.

Abstract: There are provided methods for monitoring the oligomeric content of prepolymers and polymers, which methods employ high-performance liquid chromatographic techniques. Typically, the methods of the present invention may be used to determine the oligomeric content of polyethylene terephthalate polymers and prepolymers.