Styrene Monomer Co-Production Using Waste Plastic Pyrolysis Oil
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Solution Overview
Problem
Existing processes for producing styrene monomer from waste plastic face challenges such as impurities that compromise product quality and process efficiency, including contamination with co-boilers, light molecules, unsaturated molecules, and the formation of polymers, which affect the performance of the propylene oxide and styrene monomer co-production process.
Innovation Solution
Incorporating a hydrocarbon liquid stream from the pyrolysis of styrene-enriched waste plastic into the propylene oxide and styrene monomer co-production process, utilizing fractional distillation and hydroprocessing to separate and purify ethylbenzene and alpha-methylbenzyl alcohol, followed by oxidation and dehydration to produce high-quality styrene monomer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If waste plastic pyrolysis oil is used as feedstock for styrene monomer production, then waste plastic treatment efficiency is improved, but product quality deteriorates due to impurities
Solution Approach 1:
The patent divides the complex pyrolysis oil into multiple fractions through sequential distillation operations. The process separates light molecules (C1-C4) first, then isolates styrene monomer from intermediate fractions, and finally handles heavy residues. This segmentation allows each purification step to target specific impurity ranges, achieving high product quality while processing waste plastic efficiently.
Solution Approach 2:
The patent extracts harmful impurities from the pyrolysis oil at various stages. Light molecules are removed via initial distillation, styrene monomer is extracted from the middle fraction through selective condensation, and heavy contaminants are separated in final purification steps. This systematic extraction eliminates contaminants that would otherwise compromise product quality.
2Manufacturing precision
If conventional distillation is used to separate styrene monomer from pyrolysis oil, then separation is achieved, but energy consumption increases due to multiple purification steps
Solution Approach 1:
The patent performs preliminary separation of light molecules and heavy residues before the main styrene monomer distillation. By removing these extreme fractions first, the subsequent distillation steps operate on a narrower temperature range, reducing the energy required for the critical styrene monomer separation while maintaining high purity.
Solution Approach 2:
The patent applies different distillation conditions to different fractions of the pyrolysis oil. Light molecules undergo simple distillation, the styrene monomer fraction receives controlled condensation at specific temperature ranges, and heavy residues are handled separately. This localized approach optimizes energy usage for each separation task rather than applying uniform high-energy distillation throughout.
3Adaptability or versatility
If pyrolysis oil containing xylene and other co-boilers is processed, then feedstock utilization is improved, but product contamination occurs
Solution Approach 1:
The patent uses controlled condensation as an intermediary process between distillation and final product collection. The condensation step at specific temperature ranges acts as a mediator that selectively captures styrene monomer while allowing co-boilers like xylene to remain in the vapor phase or be separated in subsequent steps. This intermediary process prevents contamination while utilizing the full pyrolysis oil feedstock.
4Productivity
If polystyrene is reproduced from pyrolysis oil, then waste plastic recycling is achieved, but product properties deteriorate compared to neat styrene
Solution Approach 1:
The patent extracts styrene monomer from the pyrolysis oil through selective distillation and condensation before it can polymerize into low-quality polystyrene. By removing and purifying the monomer first, the process prevents the formation of contaminated polymer. The extracted neat styrene monomer can then be used for high-quality polystyrene production, maintaining product properties while achieving waste plastic recycling.
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
This method allows for the efficient production of high-quality styrene monomer without additional purification steps, improving global yield and maintaining the integrity of the existing equipment, while effectively treating waste plastic.
Implementation Method 1
pyrolysis of waste plastic, such as from pyrolysis oil of waste plastics, comprising polystyrene
Implementation Method 2
fractional distillation and hydroprocessing to separate and purify ethylbenzene and alpha-methylbenzyl alcohol
Implementation Method 3
oxidation and dehydration to produce high-quality styrene monomer
Implementation Method 4
oxidation and dehydration to produce high-quality styrene monomer
Data Source
Figure 1A~1C
Figure 2A
Figure 2B
AI summary
The present invention relates to a method for the propylene oxide and styrene monomer co-production process which incorporates a hydrocarbon liquid stream resulting from the pyrolysis of waste plastic, without compromising overall performance of the process, as well as properties and quality of the different streams and final products thus obtained. The method allows reducing the synthesis de novo of styrene monomer and offers means for polystyrene waste treatment different from incineration and/or dump.