Polyurethane Alcoholysis Recovery With Phase Separation for Amine Purity
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Solution Overview
Problem
Existing methods for recovering raw materials from polyurethane materials lack efficiency in achieving optimized purity and quality, particularly in separating amine substances like toluene diamine, removing potassium ions and acid, and minimizing carbamate trapping, which are crucial for subsequent phosgenation processes.
Innovation Solution
A process involving alcoholising and hydrolysing steps with controlled water addition, followed by phase separation, purification, and distillation to recover high-purity polyol and amine substances, using catalysts and adsorbents to remove impurities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If existing chemical recycling processes are used to recover raw materials from polyurethane materials, then raw materials can be obtained, but the purity and quality of recovered polyol and amine substances are not optimized
Solution Approach 1:
The recovery process is divided into distinct stages: alcoholysis step to break down polyurethane, phase separation to divide the mixture into organic and aqueous phases, and selective purification steps for each phase. This segmentation allows targeted removal of specific impurities (amines from polyol phase, polyol from amine phase) to achieve high purity products while maintaining manageable process complexity
Solution Approach 2:
Water is introduced as an intermediary substance to facilitate phase separation and hydrolysis reactions. The water enables the separation of the reaction mixture into two phases, making it easier to isolate and purify the recovered polyol and amine substances. This intermediary approach simplifies the overall purification process while enhancing product quality
2Manufacturing precision
If amine substances are not completely separated from recovered polyol substance, then the recovery process is simpler, but the polyol substance becomes less desirable for foaming applications due to cancerogenic amine content
Solution Approach 1:
The process extracts amine substances from the polyol phase through phase separation and selective removal steps. The amines are taken out of the polyol mixture and concentrated in the aqueous phase or removed as separate byproducts, resulting in polyol substance with minimal amine content suitable for safe foaming applications
Solution Approach 2:
The process creates a purified copy of the original polyol substance by removing impurities. Through selective purification steps, a high-purity version of the polyol is produced that replicates the desired properties of virgin polyol while being free from cancerogenic amine contaminants
3Manufacturing precision
If potassium ions and acid are not removed from recovered polyol substance, then the process is simpler, but the polyol substance becomes less desirable for foaming applications
Solution Approach 1:
The process replaces complex mechanical filtration methods with chemical phase separation and selective purification. Water-soluble impurities like potassium ions and acid are removed through phase separation and washing steps, achieving high purity polyol suitable for efficient foaming applications without requiring complex mechanical separation equipment
4Manufacturing precision
If carbamate trapping is not minimized in amine recovery, then the process is simpler, but residual polyols react with isocyanates during phosgenation, reducing NCO-content and increasing solids formation risk
Solution Approach 1:
The process performs preliminary purification of the amine substance before phosgenation by removing residual polyols and carbamates through phase separation and washing steps. This preliminary action ensures that the amine feedstock for phosgenation is sufficiently pure to prevent unwanted side reactions, maintaining high NCO-content and minimizing solids formation without requiring overly complex purification equipment
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 achieves a yield of 95% or more polyol and 70% or higher amine recovery with minimized impurities, suitable for reuse in polyurethane production, addressing the challenges of purity and quality.
Implementation Method 1
a polyurethane material is alcoholised by contacting the polyurethane material with an alcoholising substance
Implementation Method 2
allowing the mixture to separate into a first phase and a second phase
Implementation Method 3
a trapping of the respective amine substance in carbamates is minimized
Implementation Method 4
using catalysts and adsorbents to remove impurities
Implementation Method 5
followed by phase separation, purification, and distillation to recover high-purity polyol and amine substances
Data Source
AI summary
A process for recovering an amine substance from a polyurethane material, preferably from an end-of-life (eol) polyurethane material, is provided, wherein the process comprises alcoholising a polyurethane material by contacting the polyurethane material with an alcoholising substance, wherein water is added in an amount so that a water content of a resulting mixture is from about 0.2 eq. to about 30 eq., based on the amount of cleavable bonds in the polyurethane material, wherein during alcoholising of the polyurethane material an amine substance and a polyol substance is formed, allowing the mixture to settle, wherein a phase, in particular a first phase, which is polyol substance rich, and a phase, in particular a second phase, which is alcoholising substance rich, are formed and wherein the process comprises a work-up of the mixture by purification of the amine substance, including distilling the phase, which is alcoholising substance rich, in particular the second phase, in a first distillation, in order to purify the amine substance, wherein the first distillation includes one or more distillation stages.