Plastic Pyrolysis Oil Purification via Solid Strong Base
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Solution Overview
Problem
Current methods for purifying plastic pyrolysis oils are inadequate in achieving high reduction performance for heteroatom concentrations, particularly chlorine, which is essential for their effective use in refining and petrochemical processes.
Innovation Solution
A process involving contact with a strong base, such as an alkali or alkaline earth metal cation in the solid state, followed by separation with a polar solvent, and optionally including steps like filtration, distillation, or catalytic hydrogenation, to reduce heteroatom content effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If plastic pyrolysis oil is treated with conventional purification methods (aqueous alkaline solutions, heat treatment with solid calcium hydroxide), then some heteroatom removal is achieved, but the reduction performance for chlorine and other heteroatoms remains insufficient
Solution Approach 1:
The patent changes the physical state parameter of the base from dissolved (conventional aqueous solutions) to solid state, and uses strong bases (NaOH, KOH) instead of weak bases (Ca(OH)2), achieving superior heteroatom removal efficiency. This parameter change transforms the purification performance from insufficient to effective.
Solution Approach 2:
The patent employs a composite approach by combining solid strong base with the pyrolysis oil and subsequently using polar solvent washing, creating a multi-stage purification system that achieves comprehensive heteroatom removal including chlorine, silicon, and nitrogen.
2Manufacturing precision
If plastic pyrolysis oil is subjected to multiple purification steps (heat treatment, distillation, hydrotreatment), then heteroatom content is reduced, but the process complexity increases
Solution Approach 1:
The patent merges the heteroatom removal function into a single integrated step by contacting the oil with solid strong base, which simultaneously removes chlorine, silicon, and nitrogen. This consolidates what would traditionally require multiple separate treatment steps into one operation, reducing process complexity.
Solution Approach 2:
The patent extracts heteroatoms directly from the pyrolysis oil through contact with solid strong base, removing impurities in one step rather than requiring sequential treatment stages. The polar solvent washing then extracts any remaining base, completing the purification efficiently.
3Productivity
If solid strong base is used for heteroatom removal, then purification efficiency increases, but the separation and removal of excess base requires additional washing steps
Solution Approach 1:
The patent uses polar solvent as an intermediary substance to facilitate the separation of excess solid base from the purified oil. The polar solvent selectively dissolves or suspends the base while leaving the hydrocarbon oil phase intact, enabling easy phase separation. This intermediary approach simplifies the removal of excess base compared to direct filtration or decanting.
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 achieves significant reductions in heteroatom concentrations, particularly chlorine, silicon, and nitrogen, enhancing the quality of plastic pyrolysis oils for subsequent use in steam cracking and other petrochemical processes.
Implementation Method 1
contacting said composition with 0.1-50% by mass of a strong base comprising an alkali or alkaline earth metal cation in the solid state
Implementation Method 2
separating the strong base comprising the alkali or alkaline earth metal cation and the product resulting from contacting said composition by washing with a polar solvent immiscible with the product resulting from step (a)
Implementation Method 3
washing with a polar solvent immiscible with the product resulting from step (a)
Data Source
AI summary
A method for purifying a composition comprising a plastic pyrolysis oil comprising a treatment with a strong base in the solid state and washing with water. The method is useful for reducing the concentration of heteroelements in said composition with a view to making it compatible for introduction as feedstock in conversion methods such as steam cracking, fluid catalytic cracking, catalytic hydrogenation or hydrocracking.