Biaryl Hydroxythiophene Group IV Catalyst for Polypropylene Tacticity Control
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Solution Overview
Problem
Current catalyst systems for propylene polymerization struggle to produce polypropylene with a range of tacticity and molecular weights, as well as olefin block copolymers containing polypropylene units, using chain transfer and chain shuttling agents.
Innovation Solution
The use of a metal-ligand complex catalyst system, specifically a complex according to formula (I), which includes a metal chosen from titanium, zirconium, or hafnium, and various ligands, in the presence of a chain transfer or chain shuttling agent to achieve the desired polymerization outcomes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional catalyst systems are used for propylene polymerization, then polymerization can proceed, but the ability to produce polypropylene with a range of tacticity and molecular weights is limited
Solution Approach 1:
The patent employs a group 4 metal catalyst with a specific ligand structure featuring aromatic rings and heteroatoms that can be modified through parameter changes in the ligand design. The ligand contains adjustable parameters such as substituent types (R1-R7 groups), heteroatom positions, and aromatic ring configurations, allowing tuning of catalyst activity, tacticity control, and molecular weight distribution while maintaining reliable polymerization performance
Solution Approach 2:
The catalyst system represents a composite structure combining group 4 metal center with a complex organic ligand framework. The ligand itself is a composite of multiple aromatic rings, heteroatom-containing groups, and substituent patterns working together to create a catalyst with enhanced versatility for producing polypropylene with controlled tacticity and molecular weight while ensuring consistent performance
2Adaptability or versatility
If chain transfer and chain shuttling agents are used with conventional catalysts, then copolymer production is attempted, but olefin block copolymers containing polypropylene units cannot be effectively produced
Solution Approach 1:
The group 4 metal catalyst with its tunable ligand structure enables effective interaction with chain transfer and chain shuttling agents. By adjusting ligand parameters such as electronic properties and steric bulk, the catalyst maintains high polymerization efficiency while gaining the ability to produce olefin block copolymers containing polypropylene units through controlled chain transfer mechanisms
3Productivity
If catalyst systems are designed for high efficiency, then production rate increases, but control over tacticity and molecular weight distribution is reduced
Solution Approach 1:
The ligand structure with its multiple adjustable parameters (substituent types, heteroatom positions, aromatic ring configurations) allows simultaneous optimization of catalyst activity for high productivity and structural features for precise control of tacticity and molecular weight distribution. The heteroatoms in the ligand provide electronic tuning while the overall ligand architecture maintains steric control
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 catalyst system enables the production of polypropylene with varied tacticity and molecular weights, as well as olefin block copolymers, effectively utilizing chain transfer and chain shuttling agents to enhance polymerization efficiency and control.
Implementation Method 1
contacting propylene and optionally one or more (C4-C12)α-olefins in a reactor in the presence of a catalyst system. The catalyst system includes a metal-ligand complex according to formula (I)
Data Source
AI summary
Embodiments of this disclosure include polymerization processes that include contacting propylene and/or one or more (C4-C12)α-olefins in a reactor including a catalyst system. The catalyst system comprises a metal-ligand complex according to formula (I).