Polyurethane Recycle Fraction Separation Using CO2-Switched Extraction
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Solution Overview
Problem
Existing methods for purifying crude polyether polyol and amine fractions from recycled polyurethane products are inefficient and costly, often requiring stoichiometric use of acids and bases, and struggle with the separation of these components due to their low water solubility and boiling point differences.
Innovation Solution
A process involving the treatment of crude polyether polyol and amine fractions with carbon dioxide to protonate amines, increasing their hydrophilicity and allowing separation into an aqueous amine fraction and an organic polyether polyol fraction, followed by heating to regenerate the amines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional acid-base extraction methods are used to separate amines and polyether polyols, then separation can be achieved, but the process requires stoichiometric use of acids and bases, increasing operational costs and complexity
Solution Approach 1:
The patent changes the chemical parameter of the extraction system by using carbon dioxide to dynamically adjust the solubility and phase distribution of amines. By controlling CO2 pressure and temperature, the amine can be selectively transferred between phases without requiring stoichiometric acid-base reagents, thereby simplifying the process while maintaining separation efficiency
Solution Approach 2:
Carbon dioxide acts as an intermediary substance that facilitates the separation process. The CO2 forms a carbamate complex with the amine, enabling selective extraction into the aqueous phase. This intermediary approach replaces the need for direct acid-base reactions, reducing process complexity and reagent consumption
2Reliability
If acid-base extraction is used for purification, then amine and polyol separation is achieved, but the cost increases due to stoichiometric reagent use
Solution Approach 1:
The carbon dioxide used in the extraction process can be regenerated and reused. After the amine is extracted into the aqueous phase as a carbamate, the CO2 can be removed by heating or pressure reduction, allowing the carbamate to decompose and release the amine. The freed CO2 can then be recycled back into the extraction system, making the process self-sufficient and eliminating the need for continuous reagent addition
Solution Approach 2:
The patent implements a recovery mechanism where the carbon dioxide, after facilitating the extraction, is discarded from the carbamate complex through thermal or pressure treatment and then recovered for reuse. This approach minimizes reagent consumption and transforms a consumable reagent process into a cyclic, sustainable process
3Reliability
If conventional distillation methods are used to separate amines from polyether polyols, then separation is possible, but the process is inefficient due to similar boiling points and low water solubility
Solution Approach 1:
Carbon dioxide serves as a mediating agent that changes the solubility characteristics of the amine. By forming a carbamate complex, the amine becomes sufficiently soluble in the aqueous phase to allow efficient liquid-liquid extraction, bypassing the limitations of conventional distillation methods that struggle with low water solubility and similar boiling points
Solution Approach 2:
The patent utilizes phase transition principles by inducing liquid-liquid phase separation through CO2 treatment. The system transitions from a homogeneous mixture to separated phases (organic polyol phase and aqueous amine phase) based on differential solubility, enabling efficient separation without relying on vapor-liquid equilibrium as in distillation
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
Facilitates efficient separation of amines and polyether polyols, reducing the need for acids and bases, and lowering operational costs while maintaining high purity of the recovered materials.
Implementation Method 1
treatment of crude polyether polyol and amine fractions with carbon dioxide to protonate amines, increasing their hydrophilicity
Implementation Method 2
protonate amines, increasing their hydrophilicity and allowing separation into an aqueous amine fraction and an organic polyether polyol fraction
Implementation Method 3
Heating and/or reducing the pressure of the separated aqueous amine fraction causes the amine hydrogen carbonates or amine carbamate salts to decompose, releasing carbon dioxide and regenerating the free amines
Implementation Method 4
treatment, in particular in the context of an extraction, of the (at least one) (crude product) fraction with carbon dioxide
Data Source
AI summary
The present invention relates to a process for the processing of a (crude product) fraction containing a polyether polyol and an amine, wherein the (crude product) fraction originates from a recycling process of a polyurethane product based on an isocyanate component and a polyol component comprising the polyether polyol, the process comprising a step (α): treatment of the (crude product) fraction with carbon dioxide and separation into an organic polyether polyol fraction and an aqueous amine fraction.