Phosphine-Phenol Half-Metallocene Catalysts for Hot Olefin Polymerization
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Solution Overview
Problem
There is an urgent need for high-performance olefin polymerization catalysts that maintain high catalytic activity at elevated temperatures and produce polyolefins with a narrower molecular weight distribution.
Innovation Solution
A phosphine-phenol half-metallocene complex is developed, featuring a specific structural formula with Group IVB metals, substituted or unsubstituted aryl groups, and halogen or hydrocarbyl substituents, which is synthesized through a simple method and used in conjunction with a cocatalyst for olefin polymerization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional phenol-phosphine zirconium complex is used for olefin polymerization, then the catalyst shows good catalytic ability, but the polymerization activity decreases significantly at higher temperatures
Solution Approach 1:
The patent modifies the ligand structure by introducing specific aromatic substituents (such as naphthyl, anthryl, or biphenyl groups) and adjusting the phosphine-to-phenol ratio, which changes the electronic and steric parameters of the catalyst complex. These parameter changes enhance the thermal stability of the catalyst, allowing it to maintain high polymerization activity at elevated temperatures (up to 80°C or higher) without significant deactivation.
Solution Approach 2:
The catalyst employs a composite ligand system combining modified phenol and phosphine components with specific aromatic hydrocarbon groups. This composite structure creates a more robust coordination environment around the zirconium center, improving the catalyst's resistance to thermal degradation while maintaining its polymerization functionality at high temperatures.
2Manufacturing precision
If conventional metallocene catalysts are used, then the catalyst structure is well-defined, but the molecular weight distribution of the produced polymer is broad
Solution Approach 1:
The patent introduces specific local modifications to the ligand structure, including substituted aromatic groups at particular positions on the phenol ring. These localized structural features create a more uniform and controlled coordination environment around the metal center, which leads to more consistent polymerization kinetics and narrower molecular weight distribution in the produced polyolefin.
3Ease of manufacture
If simple phenol-phosphine complexes are synthesized, then the synthesis method is straightforward, but the thermal stability and catalytic performance are insufficient
Solution Approach 1:
The patent employs preliminary protection and deprotection steps in the ligand synthesis, where hydroxyl groups are temporarily protected during phosphine coupling and then revealed in final steps. This preliminary action allows for cleaner reactions and higher purity products, resulting in thermally stable catalyst complexes with consistent performance.
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 complex exhibits high polymerization activity, particularly at higher temperatures, and produces polymers with a narrower molecular weight distribution and excellent copolymerization properties.
Implementation Method 1
the phosphine-phenol half-metallocene complex has good catalytic ability for olefin polymerization
Implementation Method 2
Group IV phenol-phosphine zirconium complex has good catalytic ability for olefin polymerization, and can effectively carry out ethylene or propylene polymerization reaction under the activation of cocatalyst such as methylaluminoxane (MAO)
Data Source
AI summary
The present invention relates to the technical field of olefin polymerization catalysts, and discloses a phosphine-phenol half-metallocene complex and preparation method therefor and use thereof. The structural formula of the phosphine-phenol half-metallocene complex is shown in formula (I), wherein, M is selected from Group IVB metals; Ar is selected from substituted or unsubstituted C6-C20 aryl; X is selected from halogen, C1-C10 hydrocarbyl, n is 1 or 2; L1 is selected from substituted or unsubstituted cyclopentadienyl, substituted or unsubstituted indenyl, tetrahydroindenyl, substituted or unsubstituted fluorenyl. In the case where the complex contains the same metal and the polymerization conditions are similar, when the metal complex of the present invention is used as a primary catalyst, a higher polymerization activity is achieved, the obtained polymer has an obviously lower molecular weight distribution than that of a polymer obtained in the Comparative Examples, and also has a more excellent copolymerization performance; and the metal complex of the present invention still maintains a higher polymerization activity at a higher polymerization temperature.