Waste Rubber Depolymerization to Selective C5-C7 Cycloalkenes
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Solution Overview
Problem
Chemical recycling of waste rubber is limited by complicated technology, harsh reaction conditions, low selectivity, and yield, and mechanical recycling deteriorates rubber properties, restricting its use to low-performance applications.
Innovation Solution
Depolymerization of double bond-containing polymers using an isomerization catalyst and a metathesis catalyst with a N-heterocyclic carbene ligand to produce (C5-C7)cycloalkene, employing a ruthenium complex and phosphine ligand catalysts under controlled conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If chemical recycling methods (thermal decomposition, hydrolysis, ozone decomposition) are used to recover olefin-based products from waste rubber, then product recovery is achieved, but the process requires complicated and sophisticated technology with harsh reaction conditions, resulting in low selectivity and yield
Solution Approach 1:
The patent changes the reaction parameters by using mild reaction conditions (room temperature or slightly elevated temperatures, atmospheric pressure) compared to conventional harsh methods. The key parameter change is the introduction of specific catalysts (Grubbs catalysts or Schrock catalysts for metathesis, and isomerization catalysts) that enable the reaction to proceed under gentle conditions, thereby simplifying the process while maintaining high selectivity and yield for producing (C5-C7)cycloalkene from waste rubber
Solution Approach 2:
The patent introduces catalysts as intermediaries to mediate the depolymerization and transformation of waste rubber. Specifically, metathesis catalysts (Grubbs or Schrock catalysts) and isomerization catalysts are used as intermediary substances that facilitate the chemical transformation without being consumed, enabling selective production of cycloalkene under mild conditions and avoiding the need for complicated harsh treatment processes
2Loss of substance
If conventional chemical decomposition is used, then waste rubber is converted to products, but selectivity and yield of the desired product are low, resulting in complicated mixtures
Solution Approach 1:
The patent employs specific catalysts as intermediaries to achieve selective transformation. The metathesis catalyst (Grubbs or Schrock catalyst) selectively catalyzes the metathesis reaction of double bonds in waste rubber to form cyclic structures, while the isomerization catalyst selectively isomerizes double bonds. This catalytic mediation ensures high selectivity for (C5-C7)cycloalkene production, avoiding the formation of complicated mixtures that result from non-selective conventional decomposition methods
Solution Approach 2:
The patent changes the reaction conditions to mild temperatures and atmospheric pressure, which, combined with selective catalysis, enhances the precision of the reaction. These parameter changes prevent side reactions and ensure that the transformation of waste rubber to (C5-C7)cycloalkene proceeds with high selectivity and yield, producing a purified product rather than complicated mixtures
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
High selectivity and yield of (C5-C7)cycloalkene production, enabling effective chemical recycling of waste rubber into high-value cycloalkene compounds.
Implementation Method 1
depolymerizing a double bond-containing polymer in the presence of an isomerization catalyst and a metathesis catalyst having a N-heterocyclic carbene ligand to prepare (C5-C7)cycloalkene
Implementation Method 2
depolymerizing a double bond-containing polymer in the presence of an isomerization catalyst and a metathesis catalyst
Data Source
AI summary
Provided are a method for preparing cycloalkene including: depolymerizing a double bond-containing polymer in the presence of an isomerization catalyst and a metathesis catalyst having a N-heterocyclic carbene ligand to prepare (C5-C7)cycloalkene, and a method for recycling waste rubber using the same.