Polyether Polyurethane Decomposition via Enzymatic Cleavage
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Solution Overview
Problem
Existing processes for recycling polyurethanes only recover polyether polyols, leaving behind low-molecular-weight urethanes as by-products without a satisfactory use, and do not achieve complete breakdown into chemically defined compounds.
Innovation Solution
A process involving transurethanization of polyether polyurethanes with low-molecular-weight alcohols to form polyether polyols and low-molecular-weight urethanes, followed by enzymatic cleavage of the urethanes to liberate amines and the original alcohol, allowing for the isolation and reuse of these compounds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If transurethanization is used to recover polyether polyols from polyurethanes, then polyether polyol recovery is achieved, but low-molecular-weight urethanes remain as by-products without satisfactory use
Solution Approach 1:
The patent divides the decomposition process into two distinct stages: first transurethanization to release polyether polyols, then enzymatic hydrolysis to break down the low-molecular-weight urethane by-products into useful compounds. This segmentation allows each step to be optimized independently and creates valuable products from previously wasted by-products.
Solution Approach 2:
The patent implements a continuous process where the output of the first stage (low-molecular-weight urethanes) becomes the input for the second stage (enzymatic hydrolysis). This continuous action ensures complete decomposition of polyurethane waste into useful products, eliminating the problem of unused by-products.
2Quantity of substance
If conventional transurethanization is used, then polyether polyol liberation is achieved, but complete breakdown into chemically defined compounds is not realized
Solution Approach 1:
The patent segments the decomposition process into two sequential stages: transurethanization followed by enzymatic hydrolysis. This segmentation enables complete breakdown into chemically defined compounds (polyether polyols, amines, and alcohols) rather than stopping at the intermediate urethane stage, thereby achieving both quantity and precision of product definition.
Solution Approach 2:
The patent uses an enzyme (urethane hydrolysis catalyst) as an intermediary to facilitate the second stage of decomposition. This intermediary enables the conversion of low-molecular-weight urethanes into chemically defined amines and alcohols, achieving precise chemical definition of final products that cannot be obtained through conventional transurethanization alone.
3Ease of manufacture
If low-molecular-weight alcohol is used in excess for transurethanization, then polyether polyol exchange is facilitated, but the resulting urethane mixture becomes poorly defined
Solution Approach 1:
The patent extracts and removes the problematic low-molecular-weight urethane by-products through enzymatic hydrolysis in the second stage. This extraction separates the useful polyether polyols from the poorly defined urethane mixture, converting the urethanes into chemically defined amines and alcohols, thereby resolving the contradiction between ease of manufacture and product definition.
Solution Approach 2:
The patent changes the chemical parameters of the reaction system by introducing enzymatic catalysis with specific substrate specificity. This parameter change enables selective hydrolysis of urethane bonds while maintaining the integrity of other components, transforming the poorly defined urethane mixture into chemically defined products without compromising the efficiency of the overall process.
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 process enables the complete breakdown of polyether polyurethanes into well-defined compounds, facilitating the recycling and reuse of polyether polyols and amines, while also addressing the issue of low-molecular-weight urethane by-products.
Implementation Method 1
reaction of the polyurethane with low-molecular-weight alcohols such as glycol. In such processes, an exchange of the polyether polyol for the low-molecular-weight alcohol takes place. This exchange of a polyol that is part of a urethane group for another polyol is referred to in the present patent application, by analogy with a transesterification, as a 'transurethanization'
Implementation Method 2
enzymatically cleaving the low-molecular-weight urethanes formed in process step a), with liberation of at least one amine and the at least one low-molecular-weight alcohol used in process step a)
Data Source
AI summary
A process is provided, by means of which polyurethanes, which have been formed from polyether polyols and aromatic isocyanates, can be decomposed to polyether polyols and aromatic amines.