Polyhydric Alcohol Recovery via Split-Phase Glycolysis
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Solution Overview
Problem
Current methods for recycling polyurethane waste into polyhydric alcohol are inefficient, resulting in degraded products with high viscosity, toxic by-products, and limited reuse in high-quality applications, as they fail to achieve selective and high-yield depolymerization.
Innovation Solution
A split-phase glycolysis method using a catalyst complex with magnetic nanoparticles and a polyol solvent, which separates into distinct phases to recover high-quality polyhydric alcohol, minimizing side products and achieving properties comparable to virgin polyhydric alcohol.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If linear chemical recycling method (glycolysis) is used to recycle polyurethane waste, then polyhydric alcohol can be recovered, but the product has high viscosity, dark color, and contains toxic aromatic amine by-products, making it unsuitable for high-quality applications
Solution Approach 1:
The invention changes the chemical parameters of the recycling process by using a basic catalyst (such as NaOH, KOH, or CaO) instead of conventional acidic or neutral catalysts. This parameter change in catalyst basicity enables selective cleavage of urethane bonds while minimizing side reactions that produce aromatic amine by-products, thereby improving product quality while maintaining recovery efficiency
Solution Approach 2:
The invention converts the previously harmful effect of complete depolymerization (which produced toxic by-products) into a beneficial selective cleavage process. By controlling the reaction conditions and using basic catalysts, the process selectively breaks urethane bonds to release polyhydric alcohol while leaving other components intact, thus transforming a harmful side reaction into a controlled beneficial outcome
2Manufacturing precision
If conventional depolymerization methods are used to break down polyurethane into repeating units, then polymer degradation occurs, but the process is not selective enough and produces low conversion with high waste
Solution Approach 1:
The invention employs parameter changes in catalyst type (basic catalysts like NaOH, KOH, CaO, or their salts/complexes) and reaction conditions (temperature range 150-250°C, catalyst concentration 0.1-10 wt%) to achieve both high selectivity and high conversion. These parameter optimizations enable the process to selectively target urethane bonds while maintaining fast reaction rates and high polyhydric alcohol yields
3Loss of substance
If polyurethane waste is incinerated to dispose of polymer waste, then waste volume is reduced, but energy is lost and environmental pollution increases
Solution Approach 1:
The invention implements a discarding and recovering approach by chemically depolymerizing polyurethane waste to recover valuable polyhydric alcohol that can be reused in new polyurethane production. This circular recycling method replaces linear incineration disposal, thereby reducing waste volume while recovering both material and energy value, eliminating the energy loss associated with combustion
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 method yields a polyhydric alcohol of almost equal quality to virgin alcohol, suitable for flexible foam production, with improved color, viscosity, and reduced trace metals, enhancing the recycling efficiency and product quality.
Implementation Method 1
a catalyst, which comprises catalyst particles; depolymerizing said polymer in said reaction mixture by reacting with said polyol to produce said polyhydric alcohol
Implementation Method 2
allowing said reaction mixture containing said polyhydric alcohol product to separate into an, upper, product phase containing said polyhydric alcohol and another, lower, phase mainly containing said polyol and said catalyst
Implementation Method 3
A split-phase glycolysis method using a catalyst complex with magnetic nanoparticles
Data Source
AI summary
A method is described for the production of a polyhydric alcohol from a urethane containing polymer. The method first provides a reaction mixture comprising said polymer, a reactive solvent, which comprises a polyol; and a catalyst, comprising catalyst particles. Said polymer is depolymerized in said reaction mixture by reacting with said polyol to produce said polyhydric alcohol. A further step allows said reaction mixture containing said polyhydric alcohol product to separate into a product phase containing said polyhydric alcohol and another phase mainly containing said polyol and said catalyst. The catalyst is recovered from said another phase, while said polyhydric alcohol product is recovered from said product phase. The catalyst is a catalyst complex comprising the catalyst particles and a catalyst entity covalently bonded to the catalyst particles via a linking group, wherein the catalyst entity comprises a cationic moiety having positive charge and a negative moiety having negative charge.