Silica-Supported Metathesis Catalyst for Cycloolefin Polymerization
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Solution Overview
Problem
Existing Ziegler-Natta catalyst systems for cycloolefin polymerization have undefined structures, leading to uncontrollable and non-reproducible processes, with issues such as low polymerization activity, undesirable molecular weight distributions, and the generation of hazardous catalyst poisons like HCl or Cl2.
Innovation Solution
A catalyst system comprising an isolated single-site like catalyst compound supported on materials like silica with surface OH groups, allowing for controlled activity, stereo-selectivity, and molecular weight distribution, and eliminating the need for quenching and reducing hazardous byproduct formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If homogeneous ZN catalyst systems are used for cycloolefin polymerization, then polymerization can be achieved, but the catalyst structure is undefined leading to uncontrollable and non-reproducible processes with undesirable molecular weight distributions
Solution Approach 1:
The patent applies local quality by creating well-defined local catalyst structures on silica support. The catalyst sites are localized at specific positions on the support surface with controlled geometry and electronic properties, allowing precise control over polymerization outcomes while maintaining overall process reliability.
Solution Approach 2:
The patent uses composite materials by combining transition metal compounds with silica support to create heterogeneous catalyst systems. This composite approach provides both the catalytic activity needed for polymerization and the structural stability required for reproducible, controlled processes with narrow molecular weight distributions.
2Productivity
If conventional ZN catalyst systems are used, then polymerization activity can be achieved, but catalyst poisons such as HCl or Cl2 are generated which are hazardous and reduce process efficiency
Solution Approach 1:
The patent converts the harmful generation of catalyst poisons into a beneficial process by designing catalyst systems that eliminate these harmful byproducts. The modified catalyst structure allows polymerization to proceed without generating HCl or Cl2, turning a previously harmful feature into an environmentally friendly process.
Solution Approach 2:
The patent introduces an intermediary approach by using silica support as a mediator between the transition metal catalyst and the polymerization process. This intermediary structure allows the catalyst to function efficiently while preventing the generation of harmful byproducts through controlled interaction with the monomer.
3Ease of manufacture
If homogeneous catalyst systems are used, then polymerization can be performed, but quenching steps are required to stop polymerization and separate product from catalyst residue, resulting in laborious processes with significant solvent usage
Solution Approach 1:
The patent applies segmentation by separating the catalyst from the product through the heterogeneous nature of the silica-supported catalyst. The catalyst remains on the solid support while the polymer product stays in the liquid phase, allowing simple filtration separation without requiring time-consuming quenching steps or large amounts of solvent.
Solution Approach 2:
The patent implements self-service by designing the heterogeneous catalyst system to automatically separate from the product during the polymerization process itself. The catalyst remains bound to the silica support while the polymer forms in the solution, eliminating the need for separate quenching and isolation steps.
4Productivity
If conventional catalyst systems are used, then polymerization can be achieved, but catalyst residue remains in the polymer product requiring additional purification steps
Solution Approach 1:
The patent uses segmentation to separate the catalyst (bound to silica support) from the polymer product in the liquid phase. This physical separation ensures that the polymer produced is free of catalyst residue, achieving high product purity without requiring additional purification steps while maintaining efficient polymer production.
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 solution enables controlled and reproducible cycloolefin polymerization processes, producing polymers with desired molecular weight distributions and stereo-selectivity, while allowing for the recycle of monomer, catalyst, and solvent, and eliminating catalyst residue in the polymer product.
Implementation Method 1
The active species of Ziegler-Natta ('ZN') type metathesis polymerization catalyst for cycloolefin polymerization
Implementation Method 2
catalysts constructed on silica or other supported materials containing surface OH groups
Data Source
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AI summary
A supported catalyst system is based on a transition metal carbene including the moiety Ml=CR*)2, wherein M1 is the transition metal and R* is hydrogen or a C1-C8 hydrocarbyl. The catalyst system can be supported on a metal oxide support such as silica or the catalyst can be self-supporting. Methods of making the catalyst system can involve precursors based on and/or reacted with aluminum alkyls, halides, and/or alkoxides. Methods of polymerizing cyclic olefins with the catalyst system can obtain polyalkenamers, cyclic olefin polymers, cyclic olefin copolymers, and other metathesis reaction products. The supported catalyst and/or monomer can be recovered and recycled to the polymerization reactor.