Polyurethane Depolymerization for Diisocyanate Recovery
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Solution Overview
Problem
There is a need to optimally recover and recycle di- and polyamines from polyurethane decomposition processes to produce high-quality aromatic and aliphatic di- and polyisocyanates for reuse in polyurethane production, as conventional methods are energy-intensive and inefficient.
Innovation Solution
A process involving the hydrolysis of polyurethanes in the presence of quaternary ammonium salts and organic sulfonates as catalysts, followed by extraction and phosgenation, to produce di- and polyamines, which are then converted into di- and polyisocyanates, reducing the need for energy-intensive processes like alkylation and hydrogenation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional methods (alkylation, nitration, hydrogenation) are used to produce toluene diisocyanate, then high-quality diisocyanate is obtained, but energy consumption is very high
Solution Approach 1:
The invention changes the fundamental chemical parameters of the production process by using hydrolysis of polyurethane followed by phosgenation of the resulting diamine, completely replacing the conventional multi-step alkylation-nitration-hydrogenation pathway. This parameter change reduces energy consumption while maintaining product quality.
Solution Approach 2:
The invention recovers and reuses polyurethane waste materials through hydrolysis to produce diamine, which is then converted to diisocyanate. This circular approach recovers valuable chemicals from waste streams, reducing the need for energy-intensive conventional synthesis while maintaining product quality.
2Productivity
If polyurethane decomposition processes are used to recover amines, then recycling is achieved, but the process complexity and separation requirements increase
Solution Approach 1:
The invention optimizes the hydrolysis parameters (temperature, catalyst type, base concentration) to maximize diamine yield and minimize byproducts, simplifying the subsequent separation process. By controlling these parameters, the process achieves efficient recycling while managing complexity.
Solution Approach 2:
The invention introduces specific catalysts (quaternary ammonium salts, organic sulfonates) and bases (K2CO3, Na2SiO3, NH4OH) as intermediaries to facilitate the hydrolysis reaction, improving diamine recovery efficiency and simplifying the overall process by providing controlled reaction conditions.
3Manufacturing precision
If phosgenation is used to convert amines to isocyanates, then high-quality isocyanate is produced, but phosgene handling safety risks increase
Solution Approach 1:
The invention uses phosgene as an intermediary reagent in a controlled phosgenation step, managing safety risks through proper handling procedures and process control. The phosgenation step is performed under controlled conditions to minimize safety hazards while maintaining high product quality.
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 production of high-quality aromatic and aliphatic di- and polyisocyanates, such as toluene 2,4-diisocyanate and toluene 2,6-diisocyanate, for renewed polyurethane production with reduced dichlorobenzene content, utilizing polyurethane wastes as a renewable raw material source.
Implementation Method 1
depolymerizing a polyurethane by hydrolysis in the presence of a base and a catalyst
Implementation Method 2
phosgenating the di- and/or polyamines obtained from step b) to afford di- and/or polyisocyanates
Data Source
AI summary
A process is developed for producing aromatic and/or aliphatic di- and/or polyisocyanates derived from the depolymerization of a polyurethane by hydrolysis. A composition suitable for producing polyurethane foam is made. A process is also developed for the production of polyurethane using at least one recycled isocyanate component, and a polyurethane foam is made. A process is made for manufacturing goods where the polyurethane foam is insulation, cushioning, and other similar products.