Abstract: Methods and apparatus for processing glycol according to various aspects of the present technology comprise a multi-stage treatment system that is configured to receive a feedstock from multiple waste stream sources containing glycol. A pre-treatment stage may be configured to process the incoming the feedstock and provide to a primary treatment stage a water/glycol solution that is substantially identical and allows for a primary treatment process that is not dependent upon the originating source of the glycol feedstock. A post-treatment stage may further process and purify the water/glycol solution.

Abstract: A method and apparatus are disclosed for the recovery of ethylene glycol in a polyethylene terephthalate (PET) production process, in which water accumulating in the esterification reaction is mixed with a process fluid containing 2-methyl-1,3-dioxolane (MDO). The mixing is carried out in a tank arranged upstream of a rectification column. Through the increase in the water content in the fluid, a shift in the reaction equilibrium takes place and consequently a cleavage of the 2-methyl-1,3-dioxolane present into ethylene glycol and acetaldehyde takes place. Following the cleavage reaction, the mixture is fed from the tank into a rectification column, whereby the ethylene glycol produced from the cleavage reaction is returned to the PET production process.

Abstract: Volatile compounds may be economically recovered from solids present in aqueous solution by subjecting the solution to rapid separation where the volatilization occurs in a flash, spray, or fluid bed, or mechanically agitated dryers. Rapidly separating the solids from the volatile compound greatly simplifies the isolation of the volatile compounds from water. The methods have utility for fermentation processes, solids management, and recycling processes.

Abstract: A method of decomposing wastes containing target compounds having one or more of hydrolyzable bonds of ether bond, ester bond, amide bond and isocyanate bond wherein the method comprises continuously supplying the wastes in a molten state or liquid state to a reactor, continuously supplying super-critical water or high pressure/high temperature water to the reactor, bringing the water into contact with the wastes, thereby decomposing the target compounds and then recovering them as raw material compounds or derivatives thereof for the target compounds. Target compounds contained in wastes in chemical plants which could not be utilized but merely incinerated or discarded so far are continuously decomposed into raw material compounds or derivatives thereof for the aimed compound and can be reutilized effectively.

Abstract: A method of decomposing wastes containing target compounds having one or more of hydrolyzable bonds of ether bond, ester bond, amide bond and isocyanate bond wherein the method comprises continuously supplying the wastes in a molten state or liquid state to a reactor, continuously supplying super-critical water or high pressure/high temperature water to the reactor, bringing the water into contact with the wastes, thereby decomposing the target compounds and then recovering them as raw material compounds or derivatives thereof for the target compounds. Target compounds contained in wastes in chemical plants which could not be utilized but merely incinerated or discarded so far are continuously decomposed into raw material compounds or derivatives thereof for the aimed compound and can be reutilized effectively.

Abstract: Aqueous ethylene glycol solution containing aldehydes such as formaldehyde, acetaldehyde and the like is contacted with a solid bisulfite treated strong base anion exchange resin and a solution reduced in aldehydes content is separated.

Abstract: There is described a process for purifying ethylene glycol recovered from scrap polyester by contacting the recovered ethylene glycol with, in either order, a first adsorbent that has a high affinity for polar contaminants and a second adsorbent that has a high affinity for non-polar contaminants.

Abstract: A process for preparing a recyclate polyol obtained from glycolysis of polyurethanes and/or polyurea-polyurethanes comprises reacting scrap polyurethane and/or polyurea-polyurethane with a short-chain compound containing at least 2 OH groups in the presence of a catalyst and admixing a cyclic carbonate. The process results in a recyclate polyol having a low primary aromatic amine content which may be used to produce cellular or non-cellular polyurethanes, polyurea-polyurethanes, or polyisocyanurates.

Abstract: There is described a process for removing dimethyl terephthalate contaminants from ethylene glycol. The process comprises distilling ethylene glycol in the presence of an ester exchange catalyst to cause reaction between ethylene glycol and dimethyl terephthalate to form compounds that are less volatile than either ethylene glycol or dimethyl terephthalate, such as bishydroxyethyl terephthalate.

Abstract: A method of removing dimethyl terephthalate (DMT) from a vapor stream. The vapor stream includes dimethyl terephthalate (DMT), methylhydroxyethyl terephthalate (MHET), glycols and methanol. A distillation column is held under an elevated pressure of 100 to 500 kPag and at a temperature of at least 85.degree. C. It has (i) a plurality of distillation trays; (ii) methanol liquid sprays between the trays; (iii) a main spray zone below the trays and (iv) a liquid pool of methanol in the bottom of the column. The vapor stream is directed into the distillation column, above the liquid pool and below the main spray zone, thereby forming a stream of liquid and vapor. The stream of liquid is directed away from the distillation column walls and into the liquid pool at the bottom of the column.

Abstract: A process for recovering column bottom residues produced by distillation of ethylene glycol resulting from an aromatic polyester production process, involving treating the residues with an aromatic mono-alkyl ester and distilling the reaction product.

Abstract: A process useful for the recovery of terephthalic acid and ethylene glycol from poly(ethylene terephthalate) or its copolymers. The process is economical, beneficial to the environment and provides polymer grade terephthalic acid and ethylene glycol from post-consumer resin. The process is a six-step process including: (1) contacting a resin containing poly(ethylene terephthalate) with water at elevated temperature and pressure, (2) cooling the resulting mixture to provide a solid portion containing terephthalic acid and a liquid portion containing ethylene glycol, (3) recovery of the ethylene glycol from the liquid portion by distillation, (4) recovery of the terephthalic acid by heating the solid portion in the presence of water vapor at elevated temperature to produce a vapor containing terephthalic acid and water, (5) cooling terephthalic acid water vapor mixture to a temperature below the dew point of terephthalic acid and (6) collecting the polymer grade terephthalic acid.

Abstract: There is described a process for avoiding dioxane formation during the depolymerization of polyester into glycol and ester components by passing superheated methanol through a reaction mixture containing polyester, oligomer and contaminants that are capable of forming sulfuric or halogen acids, the process comprising the step of adding sufficient base to neutralize any acid formed from the contaminants.

Abstract: Separation of ethylene glycol and diethylene glycol from dimethyl terephthalate is accomplished by distillation using methyl benzoate or the methyl ester of p-toluic acid as an azeotropic agent.

Abstract: A process for separating ethylene glycol from a mixture of ethylene glycol and dimethyl terephthalate polymers is described. The mixture is comminuted, mixed with water, and agitated at a high fluid shear rate to disperse the polymers. A flocculant and, optionally, a filter aid are added to the mixture. Thereafter, the dimethyl terephthalate polymers are separated from the mixture. The process produces a commercially valuable ethylene glycol stream. The separated dimethyl terephthalate polymers are recovered in a form which facilitates disposal or, alternatively, re-use.

Abstract: A process for recovering dimethyl terephthalate and ethylene glycol from a stream including aqueous ethylene glycol is described. Adding a dispersing agent to the stream renders it filterable, and a subsequent cooling of the stream containing the dispersing agent causes dimethyl terephthalate to precipitate in a form which can be removed by conventional filtration. The precipitated dimethyl terephthalate is of a quality and purity suitable for use in the manufacture of polyethylene terephthalate. A commercially valuable ethylene glycol stream is also recovered by the process.

Abstract: The present invention is an improved process for the recovery of ethylene glycol from spent glycol generated in the manufacture of polyethylene terephthalate. The spent glycol typically consists of metal oxide catalyst residues, low molecular weight terephthalate oligomers, diethylene glycol and other trace impurities. The improved process of the present invention is based on the principle that elevating the temperature of the spent glycol increases the solubility of the low molecular weight oligomers so that the low molecular weight oligomers can be dissolved in the ethylene glycol and further that the spent glycol at an elevated temperature may be passed through an ion exchange bed to remove metal oxide catalysts, color forming impurities and other trace impurities.

Abstract: A method to recycle spent ethylene glycol in a continuous process for the manufacture of polyethylene terephthalate in at least one reactor vessel which includes:a. condensing the overhead vapor of spent ethylene glycol, water and other byproducts from the reactor vessel,b. feeding the condensed vapor to a single distillation column,c. removing only part of the water and other byproducts from ethylene glycol by distillation overhead in the column andd. feeding the resultant bottoms of the column back to the reactor vessel as recycle ethylene glycol along with virgin ethylene glycol, so that polyethylene terephthalate polymer being manufactured by the continuous process is essentially unaffected regarding polymer color and ability to be spun into high quality yarn, but with lower diethylene glycol content that polymer made from all virgin ethylene glycol.

Abstract: A process for removing inorganic compounds from glycol recovery still bottoms resulting from the manufacture of poly(ethylene terephthalate), the novel process using a small amount of phosphoric acid to precipitate the antimony and then removing the titanium dioxide and antimony compound by a centrifuge. The novel process for removing the inorganic compounds from the recovery polyester bottoms includes the steps of distilling ethylene glycol from the spent glycol until the remaining bottoms have a solids concentration from about 15% to about 45%; adding phosphoric acid to the bottoms to form an antimony compound and removing the antimony and titanium precipitates from the bottoms by a centrifuge.

Abstract: A process is described for recovering polyester-grade ethylene glycol from crude ethylene glycol containing at least one component which has a normal boiling point below that of ethylene glycol, and which can form a UV absorber in the presence of ethylene glycol which comprises supplying to an ethylene glycol distillation system, preferably comprising a fractional distillation zone having an upper portion, a lower portion and an intermediate portion a crude ethylene glycol stream at a determined pH of less than about 7.

Abstract: This invention relates to a process for improving the ultraviolet light transmittance of ethylene glycol by treating industrial grade ethylene glycol with an aluminum-nickel alloy in the presence of an alkali compound.

Abstract: A process for the neutral hydrolytic depolymerization of condensation polymers is described. The process is conducted in a continuous manner and comprises introducing condensation polymer waste material into an aqueous hydrolysis zone at a temperature of between 200.degree. C. and 300.degree. C. and superatmospheric pressure of at least 15 atmospheres. High pressure steam is introduced into the lower portion of the hydrolysis zone underneath the level of the condensation polymer waste material. The steam serves as the principal source of heat for the hydrolysis zone. By being introduced underneath the level of the condensation polymer waste material, the steam agitates the waste material to provide heat transfer to accelerate the hydrolysis reaction. Further, a portion of the steam condenses to provide water which is a reactant in the hydrolysis reaction. An aqueous solution of the product(s) of the hydrolysis reaction is withdrawn from an upper portion of the hydrolysis zone.

Abstract: Terephthalic acid (TPA) is recovered from used polyethylene terephthalate beverage containers by reacting comminuted containers in a reaction zone with an aqueous medium containing ammonium hydroxide at elevated temperatures and pressures to form a water soluble diammonium salt of TPA, separating any undissolved solids from the reaction product, acidifying the remaining reaction product to liberate TPA, and separating the precipitated TPA. A portion of the liquid remaining after separation of TPA can be mixed with lime or slaked lime, the resulting mixture treated in an ammonia stripper to remove ammonia therefrom and the ammonia overheads from the stripper blended with another portion of the liquid remaining after separation of TPA to form a stream containing ammonium hydroxide which is recycled to the reaction zone. Ethylene glycol can be recovered from the bottoms from the ammonia stripper by distillation.

Abstract: Polyester scrap such as film (plain or silver-bearing), fabric, yarn or bottles, based primarily on polyethylene terephthalate, is depolymerized at room temperature and atmospheric pressure with a mixture of concentrated sulfuric acid and water to form crude terephthalic acid which is purified by dissolving in alkali solution, filtering to remove impurities, acidifying the filtrate to recover terephthalic acid in high yield with a purity of at least 99%.

Abstract: A process for treating butanediol obtained as a condensate during the manufacture of polybutylene terephthalate, wherein an alkali metal alcoholate or alkali metal hydride is added to the condensate at an elevated temperature. After purification, the butanediol obtained is re-used for the manufacture of polybutylene terephthalate.

Abstract: Spent ethylene glycol recovered from polyester manufacture contains dissolved antimony catalyst residues and other impurities. Prior to distillation of the spent glycol to recover purified ethylene glycol, the antimony compounds are removed by adjusting the pH of the spent glycol to about 2 to 7, preferably 5 to 7, preferably by adding an organic acid (e.g., acetic acid) adding an alkali metal borohydride (e.g., sodium borohydride) in the absence of oxygen and with intimate mixing to form a metallic antimony precipitate, and recovering the precipitate. The process is further improved by adding a catalytic amount of a strong inorganic base, e.g., sodium hydroxide, prior to the pH adjustment step, to convert any terephthalyl values to dihydroxyethyl terephthalate which can be recovered.