Polyurethane Recovery via Chemolysis and Solvent Extraction
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Solution Overview
Problem
Current chemical recycling methods for polyurethane products face challenges in achieving high-purity recovery of polyols and amines, with complexities in separating carbamates and auxiliaries, limiting industrial-scale economic viability and environmental sustainability.
Innovation Solution
A method involving chemolysis with a stoichiometric excess of alcohol and water, followed by extraction with an organic solvent at specific temperature and boiling point ranges, allowing for phase separation and subsequent distillation to obtain high-purity polyols and amines, effectively addressing the purity and separation challenges.
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 material recovery is achieved, but the separation process becomes complex and purity is difficult to achieve
Solution Approach 1:
The invention segments the recovery process into distinct stages: chemolysis to break down polyurethane into intermediate products, followed by extraction to separate these products into different phases, and finally distillation to purify individual components. This segmentation transforms a single complex separation task into manageable sequential steps, achieving high purity polyol and amine recovery without overwhelming process complexity
Solution Approach 2:
The invention introduces an intermediary extraction step using solvents to mediate between the chemolysis reaction products and the final purified components. This intermediary phase separation allows carbamates, auxiliaries, and other impurities to be selectively removed in the extraction phase, simplifying the subsequent distillation process and enabling high-purity recovery of target materials
2Manufacturing precision
If complex separation processes are used to achieve high purity polyol and amine recovery, then product purity is improved, but process complexity and economic viability worsen
Solution Approach 1:
By dividing the purification process into chemolysis, extraction, and distillation stages, the invention achieves high manufacturing precision (purity) at each step rather than requiring a single complex separation process. This segmentation makes the overall process more economically viable by using simple, well-established unit operations that can be implemented with standard equipment
Solution Approach 2:
The invention utilizes parameter changes during distillation, specifically controlling temperature and pressure conditions to selectively vaporize and condense components based on their different boiling points. This parameter-based separation achieves high purity recovery of polyols and amines through a relatively simple and economically viable distillation process
3Use of energy by moving object
If incineration is used for polyurethane waste, then energy recovery is achieved, but raw material cycling is lost
Solution Approach 1:
Instead of incineration (complete oxidation), the invention uses chemolysis conditions (reaction with alcohol and water at controlled temperatures) to selectively break down polyurethane bonds while preserving the carbon-nitrogen bonds in carbamates. This parameter change in reaction conditions enables raw material cycling by recovering intact polyol and amine molecules that can be reused in new polyurethane production
Solution Approach 2:
The invention discards the incineration approach and recovers raw materials through chemolysis followed by extraction and distillation. This discarding-and-recovering strategy transforms waste polyurethane into valuable recovered polyols and amines, closing the material cycle while still allowing energy recovery as a byproduct of the exothermic chemolysis reaction
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 method enables the recovery of polyols and amines in high purity with minimal complexity, making industrial-scale recycling economically achievable and environmentally benign.
Implementation Method 1
chemolyzing the polyurethane product with an alcohol and water
Implementation Method 2
hydrolytic cleavage of the urethane bond to recover amines
Implementation Method 3
extracting with an organic solvent having a boiling point at 1013 mbar(abs.) in the range from 40° C. to 120° C.
Implementation Method 4
phase separation into a first product phase and a second product phase
Implementation Method 5
separating off organic solvent by distillation and/or stripping
Implementation Method 6
separating off amine dissolved in the first product phase by distillation to obtain the polyol
Data Source
AI summary
The present invention relates to a method for recovering at least one raw material from a polyurethane product, comprising steps (A) providing a polyurethane product based on an isocyanate component and a polyol component, the isocyanate component comprising only isocyanates for which the corresponding amines have a boiling point at 1013 mbar(abs.) of at most 410° C.; (B) performing chemolysis of the polyurethane product with an alcohol and water; (C) processing the product of the chemolysis, comprising (C.I) extraction with an organic solvent, the boiling point of which at 1013 mbar(abs.) is in the range of 40° C. to 120° C., at a temperature in the range of 10° C. to 60° C., followed by (C.II) phase separation into a first product phase and into a second product phase; and (D) processing the first product phase to obtain the polyol, comprising (D.I.) separation of organic solvent by distillation and/or stripping, and (D.II) separation of amine dissolved in the first product phase by distillation so as to obtain the polyol.