PET Oligomer Recycling at Controlled Temperature for Impurity Removal
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Solution Overview
Problem
Existing chemical recycling methods for polyethylene terephthalate (PET) are energy inefficient, ecologically unfriendly, have low throughput, and produce degradation products that are difficult to remove, often requiring mixing with virgin PET to achieve high-quality recycled products.
Innovation Solution
A method involving specific temperature ranges and organic compounds to process PET flakes, using particulated materials for adsorption, de-coloring, and filtration to produce PET oligomers, which are then polymerized into high-quality PET polymers with reduced impurities and energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If PET is depolymerised to monomers using conventional chemical recycling methods, then chemical components are obtained for producing recycled PET, but the process requires long depolymerisation times and produces large amounts of degradation products that cannot be removed from the recycled PET
Solution Approach 1:
The patent applies parameter changes by controlling the depolymerisation temperature within a specific range of 160-230°C and using a mass ratio of PET to organic compound between 1:2 and 1:10. These parameter optimizations enable selective depolymerisation that produces oligomers with fewer degradation products while maintaining reasonable processing time, resolving the contradiction between complete depolymerisation and degradation product formation
Solution Approach 2:
The patent employs partial action by stopping the depolymerisation process at the oligomer stage rather than complete monomer conversion. This partial depolymerisation approach produces PET oligomers that can be directly used for polymerisation without requiring complete breakdown to monomers, thereby reducing degradation product formation while maintaining acceptable depolymerisation efficiency
2Productivity
If conventional chemical recycling methods are used to produce recycled PET, then PET waste is processed, but the process is very energy inefficient and ecologically unfriendly
Solution Approach 1:
The patent optimizes energy efficiency by implementing controlled temperature ranges (160-230°C) and optimized mass ratios of PET to organic compound (1:2 to 1:10). These parameter changes enable the depolymerisation process to proceed at moderate temperatures with improved energy efficiency compared to conventional high-temperature methods, while maintaining productive throughput
Solution Approach 2:
The patent introduces organic compounds as intermediaries to facilitate the depolymerisation process. These organic compounds act as mediators that enable selective cleavage of PET bonds under milder conditions, reducing energy consumption while maintaining recycling throughput. The intermediary substances help achieve efficient polymer breakdown without requiring excessive energy input
3Manufacturing precision
If PET is chemically recycled to high quality, then recycled PET product quality improves, but it is required to mix the recycled PET with virgin PET
Solution Approach 1:
The patent achieves high-quality recycled PET by controlling depolymerisation parameters (temperature 160-230°C, mass ratio 1:2 to 1:10) that produce oligomers with minimal degradation products. This precise parameter control ensures the recycled PET meets high quality standards without requiring blending with virgin PET, eliminating the loss of substance associated with mixing requirements
4Productivity
If higher temperatures are used to increase throughput in PET processing, then production speed increases, but energy consumption increases and degradation products increase
Solution Approach 1:
The patent resolves this contradiction by identifying an optimal temperature window of 160-230°C that balances throughput with energy efficiency and product quality. Within this parameter range, the process achieves adequate processing speed without the excessive energy consumption and degradation product formation associated with higher temperatures, demonstrating optimized parameter selection
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method enhances the production of high-purity PET oligomers and polymers with improved color quality, increased throughput, and reduced energy use, extending equipment lifetime and minimizing environmental impact.
Implementation Method 1
reducing a weight average molar mass of the first polyester to obtain a first intermediate mixture, wherein the first intermediate mixture comprises i. a first intermediate product
Implementation Method 2
adding first particulated material to the first intermediate mixture in a volume section V4
Implementation Method 3
a temperature of the first intermediate mixture in the volume section V4 is in the range of 160° C. to 230° C.
Data Source
AI summary
One aspect is a method for producing a first intermediate product. A feedstock is provided that comprises a first polyester. The first polyester is contacted with a further organic compound in a volume section V3 to obtain a further initial mixture.A weight average molar mass of the first polyester is reduced in the volume section V3 to obtain a first intermediate mixture. The first intermediate mixture comprisesa first intermediate product and;the further organic compound.First particulated material is added to the first intermediate mixture in a volume section V4.A temperature of the first intermediate mixture in the volume section V4 is in the range of 160° C. to 230° C.