Glycolysis for PET Bottle Recycling

Method for recycling waste polyester like PET bottles into usable polyester by alcoholysis with ethylene glycol catalyzed by a two-component catalyst of nitrogen-containing polycyclic organic matter and metal salts like zinc acetate. The catalyst synergistically accelerates ester bond cleavage compared to single components. The timing of adding the nitrogen compound is critical to avoid decomposition. The method involves heating crushed PET in ethylene glycol with metal salt, then adding the nitrogen catalyst. The alcoholysis completes when PET disappears. This gives high-purity recycled BHET for repolymerization.

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Recycling of polyethylene terephthalate (PET) waste into new PET using a two-step process that involves partial depolymerization followed by full depolymerization. The process reduces the amount of ethylene glycol and catalyst needed compared to conventional glycolysis. It also shortens the depolymerization time. The process involves mixing PET with ethylene glycol at 200-250°C for partial depolymerization. Then, contacting the partially depolymerized PET with ethylene glycol and catalyst at 170-200°C for full depolymerization. This yields bis(2-hydroxyethyl) terephthalate (BHET) with lower ethylene glycol and catalyst consumption, and shorter time compared to direct glycol

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Method for producing high purity bis-2-hydroxyethyl terephthalate (BHET) from waste polyester through multi-stage depolymerization and separation. The method involves depolymerizing waste polyester using two-stage glycolysis reactions at lower temperatures, followed by ion exchange, distillation, and final distillation steps to remove impurities and unreacted glycols. This reduces contaminants like diethylene glycol esters that degrade BHET properties when recycling waste polyester. The resulting BHET has high purity and quality for use in polyester production.

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Enzymatic method for recycling post-consumer PET bottles by depolymerizing them into a more useful form for repolymerization. The method involves using enzymes to hydrolyze the PET into bisphenol A ethylene glycol terephthalate (BHET) esters. This is done by soaking the PET in ethylene glycol at 70°C with enzymes for several hours. The BHET esters can then be used as a feedstock for new PET production, avoiding the need for virgin petroleum-based terephthalic acid.

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Recycling of polyester waste like colored and opaque PET bottles to produce new polyester resin. The recycling method involves conditioning the feedstock containing colored and opaque PET by extruding and mixing it with ethylene glycol. This conditioning step improves the depolymerization efficiency by breaking down the polymer structure. The conditioned feed is then depolymerized in a reactor using a catalyst to produce monomers. The monomers are separated and purified to obtain a recycled polyester resin. The conditioning step is crucial for recycling high-impurity PET feedstocks like colored and opaque PET with high pigment content.

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A process for depolymerizing recycled polyesters containing opaque polyethylene terephthalate (PET) to recover monomers. The process involves conditioning the feedstock, glycolysis at high temperature and pressure, separating the diols, and final separation of the monomers. The high temperature and short residence times prevent pigment catalysis and blockage. The diol separation removes impurities. This allows recycling of feedstocks with high opaque PET content that can't be filtered out.

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Optimized method for recycling colored and opaque polyester, like PET, by glycolysis depolymerization followed by purification. The method involves conditioning the polyester feedstock, depolymerizing it in the presence of diols like ethylene glycol, separating unreacted diols, and then purifying the diols before recycling. This allows recovering high purity BHET diester from colored and opaque PET without aggregation issues. The diol separation and purification steps are integrated with the glycolysis step to reduce energy consumption.

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Process and plant for recycling waste polyethylene terephthalate (PET) by glycolysis into monomers. The process involves mixing PET and ethylene glycol (EG) in a blender at elevated temperatures to collapse the PET and facilitate mixing. Then, the PET-EG slurry is fed into a screw press to squeeze out excess EG. The PET-EG mixture is further glycolyzed in a paddle reactor. The process allows depolymerizing heterogeneous waste PET without grinding or drying by using EG in all steps. The plant has a blender, screw press, and paddle reactor.

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Method for preparing a high-purity, high-yield monomer from waste PET plastic, and using it to make thermoplastic polymers with improved properties. The process involves glycolysis of waste PET with ethylene glycol and a catalyst like zinc acetate or sodium bicarbonate at 180-200°C. This converts the PET into bis(hydroxyethyl) terephthalate (BHET) monomer. The BHET can then be used to make thermoplastic polymers like polyurethanes.

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Integrated process for recycling polyester like PET that allows recycling of opaque PET with high filler content. The process involves depolymerizing the feedstock using glycolysis, separating the diester fraction, purifying it, then condensing it with terephthalic acid and diol to make new PET. This allows extracting and recycling the valuable terephthalic acid and diester components from opaque PET, avoiding issues with clogging pigments. The process also involves treating the glycol and diol effluents to recover and recycle those as well.

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Enzymatic recycling of post-consumer PET plastic waste into new PET using glycolysis. The process involves breaking down the polyester structure of PET into bis-hydroxyethylene terephthalate (BHET) monomers using enzymes. The enzymatic glycolysis reaction is carried out on pretreated PET waste, such as ground-up bottles, to enrich the BHET content. The BHET-rich stream can then be repolymerized into new PET. The enzymatic recycling avoids using catalysts that could contaminate the recycled PET.

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Chemically recycling polyethylene terephthalate (PET) waste to directly obtain low-viscosity polyols for making unsaturated esters and polyurethanes. The recycling process involves depolymerizing PET waste with excess glycols and a catalyst to form oligomers. Then, adding a chelating agent to recover residual glycols under reduced pressure while stopping the catalyst. This prevents polymerization and allows isolating low-viscosity polyols. The chelating agent removes the catalyst's function, controlling molecular weight.

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Recycling waste PET into polyester with improved transparency using waste polyethylene terephthalate. The recycling includes melting a mixture including a polyethylene terephthalate component and a diol component including cyclohexanedimethanol to proceed with a glycolysis reaction.

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Recycling of transparent PET waste like bottles, textiles, and film into food-safe PET resin using chemical glycolysis. The process involves cleaning, drying, sorting, and extracting metals/non-PET fractions from the PET waste. Then, the cleaned PET is depolymerized into monomers using an extruder. The monomers are mixed and filtered to produce a food-grade PET resin suitable for contact with food.

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Recycling waste PET plastic bottles by using propylene glycol as a solvent and catalyst to degrade the PET into monomer ethylene terephthalate (ETP) and propylene glycol oligomers. The process involves cutting the PET bottles, washing, drying, then heating them in propylene glycol at 180-200°C for 4-6 hours with a catalyst like phosphoric acid or phosphotungstic acid. This selectively breaks down the PET into ETP monomers that can be further polymerized into new PET, while avoiding the formation of undesirable byproducts like terephthalic acid or oligomers that would impede recycling.

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Chemical recycling of waste PET bottles into BHET (bis(2-hydroxyethyl) terephthalate) using a low cost, short time, atmospheric pressure, and relatively low temperature recycling system. The recycling involves degrading waste PET with ethylene glycol and an ionic liquid catalyst to form BHET. The system includes feeding systems for PET, ethylene glycol, and catalyst, degradation and filtration reactors, cooling crystallization, and separating BHET from glycol. The energy recovery is achieved by heating/cooling between the PET and glycol tanks.

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Chemical recycling of PET waste to minimize waste and increase recovery compared to physical recycling. The process involves separating foreign matter from the PET waste, recovering the PET-rich stream, and then reacting that stream with glycol to produce bis-hydroxyethyl terephthalate (BHET) again. This allows separating and recycling the valuable BHET while avoiding issues like coating separation in physical recycling. The foreign matter is removed in steps between the PET reactors. The remaining residue is reacted with methanol to recover BHET again.

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