Polyurethane Alcoholysis Recovery With Solvent Phase Separation
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Solution Overview
Problem
Existing chemical recycling methods for polyurethane products face challenges in achieving high purity recovery of polyols and amines, while efficiently separating and recycling auxiliaries and additives, making industrial-scale implementation economically viable and environmentally benign.
Innovation Solution
A method involving reacting polyurethane products with alcohol in the presence of a catalyst, followed by mixing with a miscible organic solvent, washing with an aqueous liquid to hydrolyze carbamates, and separating phases to recover polyols and amines, with optional further processing to obtain isocyanates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If chemical recycling methods are used to recover polyols and amines from polyurethane products, then raw materials can be recovered, but the purity of recovered polyols and amines is insufficient
Solution Approach 1:
The invention divides the recovery process into distinct stages: (A) alcoholysis reaction to break down polyurethane, (B) filtration to remove solids, (C) extraction with organic solvent to separate polyols from aqueous phase, and (D) distillation to purify the extracted polyols. This segmentation allows each step to address specific purification needs, achieving high purity recovered materials.
Solution Approach 2:
The invention uses liquid-liquid extraction with an organic solvent (such as dichloromethane, chloroform, or carbon tetrachloride) to selectively extract polyols from the aqueous reaction mixture. The organic solvent forms a separate phase where polyols partition into, allowing their separation from water-soluble impurities and amines. This extraction step is crucial for achieving high purity.
Solution Approach 3:
The invention creates different local environments for different components: the aqueous phase contains water-soluble substances (amines, catalysts), while the organic solvent phase concentrates polyols. By controlling the local chemical environment in each phase and using selective solubility, the process achieves high purity separation of different components.
2Loss of substance
If chemical recycling methods are used to recover polyols and amines, then raw materials can be recovered, but the complexity of the process increases
Solution Approach 1:
The process is divided into clear sequential steps (A-D) that can be implemented using standard equipment. Each step has a specific function: reaction, filtration, extraction, and distillation. This segmentation makes the complex process manageable and scalable for industrial application.
Solution Approach 2:
The organic solvent acts as an intermediary substance that facilitates the separation of polyols from the reaction mixture. It temporarily holds the polyols in a separable phase, enabling their isolation without requiring complex direct separation equipment. The solvent can be recovered and reused, adding to process efficiency.
3Loss of substance
If conventional chemical recycling is used, then polyols can be recovered, but auxiliaries and additives cannot be effectively separated and reused
Solution Approach 1:
The process separates different types of substances into different phases: polyols go to the organic solvent phase, while amines, catalysts, and water-soluble additives remain in the aqueous phase. Solid additives are removed by filtration. This segmentation enables selective recovery and reuse of different components.
Solution Approach 2:
The extraction step selectively takes out polyols into the organic phase, leaving behind water-soluble substances including many additives and catalysts in the aqueous phase. This allows for selective recovery of polyols while concentrating other substances for separate handling or recovery processes.
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 achieves high-purity recovery of polyols and amines, facilitates the recycling of auxiliaries and additives, and allows for the reuse of reagents, enhancing the economic viability and environmental sustainability of the process.
Implementation Method 1
reacting the polyurethane product with an alcohol in the presence of a catalyst, to give a first product mixture containing alcohol, polyols and carbamates
Implementation Method 2
washing the second product mixture obtained in step (C.I) with an aqueous wash liquid, whereby carbamates present in the second product mixture are partially hydrolyzed to release amines and alcohol
Implementation Method 3
phase separation into a first solvent phase containing organic solvent used in step (C.I) and polyols, and a first aqueous phase containing water, alcohol, carbamates and amines
Data Source
AI summary
The invention relates to a method for recovering raw materials from polyurethane products, having the steps of: (A) providing a polyurethane product based on an isocyanate component and a polyol component; (B) reacting the polyurethane product with an alcohol in the presence of a catalyst, wherein a first product mixture containing alcohol, polyols, carbamates, and optionally water is obtained; (C) preparing the first product mixture, having the steps of: (C.I.) mixing the first product mixture obtained in step (B) with an organic solvent, which can be mixed with the alcohol used in step (B), optionally followed by a separation of solid components, thereby obtaining a second product mixture; (C.II) washing the second product mixture obtained in step (C.I) using an aqueous washing fluid, wherein carbamates contained in the second product mixture are hydrogenated partly while releasing amines and alcohol, and carrying out a phase separation into a first solvent phase, containing the organic solvent used in step (C.I) and polyols, and a first aqueous phase, containing water, alcohol, carbamates, and amines; and (C.III) processing the first solvent phase, thereby obtaining the polyols; and optionally (D) processing the first aqueous phase, thereby obtaining an amine which corresponds to an isocyanate of the isocyanate component.