Waste Plastic Oil Purification via Diene Oligomerization
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Solution Overview
Problem
The pyrolysis plastic oil obtained from plastic pyrolysis contains large quantities of dienes, which react easily forming gums and act as coke precursors, preventing its direct use in a steam cracker without pre-treatment.
Innovation Solution
A process involving cationic polymerization of the pyrolysis plastic oil to convert dienes into oligomeric products, followed by neutralization with a basic compound, washing, and separation to remove impurities, enabling further use in processes like steam cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If pyrolysis plastic oil is used directly in a steam cracker without pre-treatment, then the process is simple and fast, but the dienes in the oil react easily forming gums and coke precursors, reducing reliability and causing operational problems
Solution Approach 1:
The patent applies preliminary action by performing cationic polymerization of dienes before the steam cracking process. The dienes are converted into oligomeric products in advance, preventing them from forming gums and coke during subsequent processing. This pre-treatment step ensures operational reliability while maintaining efficient processing.
2Reliability
If purification steps are added to remove dienes from pyrolysis plastic oil, then reliability and product quality improve, but device complexity and process steps increase
Solution Approach 1:
The patent changes the chemical state of dienes through cationic polymerization, converting them from reactive monomeric dienes into less reactive oligomeric products. This parameter change in molecular structure and reactivity effectively removes the harmful effects of dienes while using a chemically efficient process that doesn't require complex multi-step purification equipment.
3Manufacturing precision
If cationic polymerization is performed to convert dienes into oligomeric products, then diene content is reduced and oil quality improves, but additional process steps and basic compounds are required
Solution Approach 1:
The patent converts the harmful reactive dienes into beneficial oligomeric products through cationic polymerization. The dienes, which originally caused gum formation and coke precipitation, are transformed into stable oligomers that can be easily separated. This approach turns a process problem into a solution, achieving purification while creating valuable intermediate products.
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 process effectively reduces diene content to less than 5.0 wt.%, allowing the purified pyrolysis plastic oil to be used in steam crackers and producing valuable olefins such as ethylene and propylene.
Implementation Method 1
performing a neutralization reaction by contacting said first product stream with a basic compound to obtain a neutralized product stream
Implementation Method 2
performing a separation to separate the oligomeric product from the purified liquified waste polymer
Data Source
AI summary
The disclosure relates to the purification and treatment of oil produced from the liquefaction of waste polymer like for instance the pyrolysis of waste plastics via the polymerization of dienes prior to further treatments.