Polyurethane Cleaving Catalyst System for Chemical Recycling
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Solution Overview
Problem
Current chemical recycling methods for polyurethanes face inefficiencies and produce discolored products with high by-product content, making it difficult to recycle raw materials effectively and economically, especially due to high reaction temperatures and the formation of unusable N-alkylated compounds.
Innovation Solution
A method of chemolysis using a catalyst salt of an oxoacid from the fifth, fourteenth, or fifteenth group of the Periodic Table with a pKB value between 0.10 and 6.00, excluding carbonates, orthophosphates, and metaphosphates, for alcoholysis, hydrolysis, or hydroalcoholysis of urethanes, allowing for efficient cleavage at lower temperatures and avoiding the formation of unusable by-products.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional chemical recycling methods are used to cleave polyurethanes, then the urethane bonds can be broken down, but the reaction requires high temperatures and produces discolored products with high by-product content including unusable N-alkylated compounds
Solution Approach 1:
The patent changes the chemical parameters of the reaction system by introducing a specific catalyst system (metal salts from groups 1, 2, 13, or 14 with pKB values between 0.10 and 6.00) and controlling the alcohol-to-urethane ratio. These parameter changes enable the reaction to proceed at lower temperatures (80-150°C) while minimizing by-product formation and avoiding discoloration, thus resolving the contradiction between bond cleavage efficiency and product quality.
Solution Approach 2:
The patent employs metal salt catalysts as intermediaries to facilitate the chemolysis reaction. These catalysts (such as sodium acetate, potassium acetate, zinc acetate, aluminum acetate) act as mediators that lower the activation energy required for urethane bond cleavage, enabling the reaction to proceed under milder conditions with higher selectivity and fewer by-products, thereby improving product quality while reducing harmful by-product formation.
2Productivity
If high reaction temperatures are applied to achieve efficient cleavage of urethane bonds, then the reaction rate increases, but this leads to formation of unusable N-alkylated compounds and discolored products
Solution Approach 1:
The patent changes the temperature parameter from conventional high temperatures to a optimized range of 80-150°C, combined with the use of specific metal salt catalysts. This parameter change maintains high reaction rates (efficient productivity) while preventing the formation of N-alkylated by-products and discoloration, thus resolving the contradiction between reaction rate and product quality.
Solution Approach 2:
The metal salt catalysts serve as intermediaries that provide an alternative reaction pathway with lower activation energy. This allows the reaction to proceed rapidly at moderate temperatures (80-150°C) without requiring high temperatures that would lead to unwanted side reactions and product degradation, thereby maintaining both high productivity and manufacturing precision.
3Loss of substance
If conventional catalysts are used for chemolysis, then the cleavage reaction can proceed, but the raw materials cannot be effectively recovered and recycled due to high by-product content
Solution Approach 1:
The patent employs metal salt catalysts (from groups 1, 2, 13, or 14 with specific pKB values) as intermediaries that enable selective cleavage of urethane bonds. These catalysts promote the formation of desired products (amines and polyols) while minimizing by-product formation, thereby enabling effective recovery and recycling of raw materials and reducing substance loss.
Solution Approach 2:
The patent optimizes reaction parameters including temperature (80-150°C), alcohol-to-urethane ratio (2:1 to 10:1), and catalyst concentration. These parameter changes enhance the selectivity of the chemolysis reaction, maximizing raw material recovery while minimizing by-product content, thus resolving the contradiction between substance recovery and by-product formation.
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
Enables efficient cleavage of urethane bonds with minimal by-product formation, facilitating the recovery of valuable raw materials such as polyols and amines, which can be reused in polyurethane production, thus improving the economic and environmental sustainability of polyurethane recycling.
Implementation Method 1
The present invention relates to a method of cleaving urethanes, especially polyurethanes, by chemolysis (alcoholysis, hydrolysis or hydroalcoholysis) in the presence of a catalyst
Implementation Method 2
the catalyst used is a salt of an oxoacid of an element from the fifth, fourteenth or fifteenth group of the Periodic Table of the Elements or a mixture of two or more such acids, where the pKB of the anion of the salt of the oxoacid is in the range from 0.10 to 6.00
Data Source
AI summary
The invention relates to a method for cleaving urethanes, in particular polyurethanes, by means of chemolysis (alcoholysis, hydrolysis, or hydroalcoholysis) in the presence of a catalyst. The chemolysis is characterized in that a salt of an oxyacid of an element of the fifth, fourteenth, or fifteenth group of the periodic table of elements or a mixture of two or more such salts is used as the catalyst, the pKb value of the anion of said salt of the oxyacid ranging from 0.10 to 6.00, preferably 0.25 to 5.00, particularly 0.50 to 4.50, wherein the catalyst does not comprise carbonate when the chemolysis is carried out as an alcoholysis (Ia), and the catalyst does not contain carbonate, orthophosphate, or metaphosphate when the chemolysis is carried out as a hydroalcoholysis.