Polyurethane Raw Material Recovery via Alcoholysis and Phase Separation
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Solution Overview
Problem
Existing chemical recycling processes for polyurethane products face challenges in achieving high-purity recovery of polyols and amines, while also efficiently separating and recycling auxiliaries and additives, which limits large-scale economic viability and environmental sustainability.
Innovation Solution
A process involving alcoholysis without significant water addition, followed by phase separation with an immiscible organic solvent, and optional hydrolysis of carbamates to recover polyols and amines, with specific solvent and catalyst choices to enhance purity and recyclability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If chemical recycling processes are used to recover polyols and amines from polyurethane products, then raw material recovery is achieved, but the purity of recovered polyols and amines is insufficient
Solution Approach 1:
The recycling process is divided into multiple sequential stages: (1) alcoholysis reaction to break down polyurethane, (2) filtration to remove solid auxiliaries and additives, (3) distillation to separate and purify polyols and amines from the reaction mixture. This segmentation allows each stage to target specific impurities, progressively increasing purity while maintaining high recovery rates of raw materials.
Solution Approach 2:
The patent introduces an intermediary filtration step using filter media specifically designed to capture fine particulate matter, catalyst residues, and other solid contaminants. This intermediary separation process acts as a bridge between the reaction stage and the final purification stage, removing problematic impurities that would otherwise co-distill with the target products and reduce purity.
2Loss of substance
If chemical recycling processes are used to recover polyols and amines, then raw material recovery is achieved, but the separation and recycling of auxiliaries and additives becomes inefficient
Solution Approach 1:
The patent employs selective extraction techniques where specific solvents or separation media are introduced to selectively bind and remove auxiliaries and additives from the reaction mixture. These extracted impurities are then concentrated and separated in dedicated purification units, allowing the main product stream (polyols and amines) to proceed to distillation without contamination, thereby improving both recovery efficiency and overall productivity.
3Loss of substance
If existing chemical recycling processes are used, then polyurethane waste can be processed, but the process is not economically viable for large-scale application
Solution Approach 1:
The patent implements a comprehensive recovery system where not only the target products (polyols and amines) are recovered through distillation, but also the solvents, catalysts, and other process chemicals are captured and regenerated in separate units. This multi-stream recovery approach minimizes material loss and reduces the cost of raw material inputs, improving the economic viability of large-scale operation.
Solution Approach 2:
The patent designs integrated processing units that perform multiple functions: reaction vessels that also serve as separation chambers, combined filtration-distillation systems, and multi-purpose catalyst recovery units. This multi-functionality reduces the total number of equipment pieces required, lowers capital investment costs, and simplifies plant operation, making large-scale deployment economically attractive.
4Loss of substance
If existing chemical recycling processes are used, then polyurethane waste can be processed, but the process is not environmentally sustainable
Solution Approach 1:
The patent converts the harmful aspect of polyurethane waste (persistent polymer material requiring disposal) into a beneficial resource stream. Through controlled alcoholysis and systematic separation, the waste is transformed into valuable raw materials (polyols and amines) that can be fed back into production, creating a circular economy model that eliminates waste disposal issues and reduces the need for virgin material extraction.
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
Enables efficient recovery of high-purity polyols and amines, along with effective separation and recycling of auxiliaries, making the process economically and environmentally viable for large-scale polyurethane recycling.
Implementation Method 1
reacting the polyurethane product with a (mono- or polyhydric) alcohol in the presence of a catalyst to obtain a first product mixture
Implementation Method 2
Mixing the first product mixture obtained in step (B), without prior separation of any water present in the first product mixture, with an organic solvent which is not completely miscible with the alcohol used in step (B), and phase separation into a first alcohol phase and a first solvent phase
Implementation Method 3
removing the water remaining after hydrolysis from said solution
Implementation Method 4
Processing the first solvent phase to obtain polyols
Data Source
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AI summary
The invention relates to a method for recovering raw materials from polyurethane products, comprising the steps of (A) providing a polyurethane product that is based on an isocyanate component and a polyol component; (B) reacting the polyurethane product with a (mono- or polyvalent) alcohol in the presence of a catalyst, thereby obtaining a first product mixture; (C) obtaining the polyols from the first product mixture, comprising (C.I) mixing, without prior removal of any water that might be contained in the first product mixture, the first product mixture obtained in step (B) with an organic solvent that is not completely miscible with the alcohol used in step (B), and phase separation into a first alcohol phase and a first solvent phase; (C.II) processing the first solvent phase and obtaining polyols; and preferably (D) obtaining amines.