Abstract: Disclosed is an optimized system for more efficiently and economically producing terephthalic acid. The system includes an oxidative digestion reactor/zone configured to provide optimized residence time distribution for the solid and liquid phases of the reaction medium processed therein.

Abstract: Disclosed is an optimized system for more efficiently and economically producing terephthalic acid. The system includes an novel method for heating the slurry and/or reaction medium subjected to oxidative digestion.

Abstract: Disclosed is an optimized system for more efficiently and economically producing terephthalic acid. The system includes an novel method for heating the slurry and/or reaction medium subjected to oxidative digestion.

Abstract: Disclosed is an optimized system for more efficiently and economically producing terephthalic acid. The system includes an oxidative digestion reactor/zone configured to provide optimized residence time distribution for the solid and liquid phases of the reaction medium processed therein.

Abstract: A process for producing high quality TPA suitable for PET feedstock material from recycled polyester. The process includes the steps of depolymerizing the polyester to form DMT; separating the DMT from secondary materials; and hydrolyzing the DMT to form TPA. In a preferred embodiment of the invention the recycled polyester is contacted with a component monomer or oligomer thereof to liquefy the polyester prior to depolymerizing the polyester.

Abstract: Disclosed herein is a process for depolymerizing and purifying contaminated post-consumer polyester. In the process, depolymerization is effected by way of glycolysis in an agitated reactor vessel. The process includes the steps of contacting a contaminated polyester with an amount of a glycol to provide a molar ratio of greater than about 1 to about 5 total glycol units to total dicarboxylic acid units at a temperature between about 150 to about 300° C. and an absolute pressure of about 0.5 to about 3 bars. This reaction is conducted for a time sufficient to produce, in the reactor, an upper layer having a relatively low density contaminant floating on top of a lower layer which includes a relatively high density depolymerized oligomer of the polyester, and separating the upper layer from the lower layer. The layers may be separated by removing the upper layer from the reactor in a first stream and removing said lower layer from the reactor in a second stream.

Abstract: Disclosed is a process for the production and purification of dialkyl naphthalenedicarboxylate compounds wherein a crude naphthalenediacarboxylic acid is esterified with an alkanol such as methanol to produce a crude esterification product comprising dialkyl naphthalenedicarboxylate, starting materials and other compounds and the crude esterification product is purified by flash distillation to remove impurities which can cause fouling of conventional distillation equipment. A particularly useful diester is dimethyl 2,6-naphthalenedicarboxylate.

Abstract: An apparatus for depolymerizing recycled polyester into its component ester monomers and half esters includes a first reactor for depolymerizing the recycled polyester, a separator for separating ester monomeric components and half-esters from secondary materials produced in the first reactor, and a second reactor for producing a low molecular weight polyester from liquefied separator products.

Abstract: A process for recovering suitable polyester feedstock material from recycled polyester includes the steps of depolymerizing the polyester into its component ester monomers and half-esters; separating the monomers and half-esters from other secondary materials; and mixing the component ester monomers and half-esters with additional monomers to produce a low molecular weight polyester. In a preferred embodiment of the invention the recycled polyester is contacted with a component monomer or oligomer thereof to liquefy the polyester before the polyester is depolymerized.The invention further provides an apparatus for carrying out the process. The apparatus includes a first reactor for depolymerizing the recycled polyester, a separator for separating ester monomeric components and half-esters from secondary materials produced in the first reactor, and a second reactor for producing a low molecular weight polyester from the liquefied separator products.