Twelve-Membered Ring Cocatalyst for Olefin Polymerization
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Solution Overview
Problem
Current catalyst systems for olefin polymerization struggle to achieve high stereospecificity and hydrogen modulation sensitivity simultaneously, which are crucial for producing polypropylene with high isotactic index and low ash content.
Innovation Solution
Incorporating a twelve-membered ring compound as a cocatalyst with a Ziegler Natta-type main catalyst, specifically a solid catalyst component containing magnesium, titanium, and an internal electron donor, to enhance polymerization activity and stereospecificity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional electron donor compounds are used in Ziegler Natta catalyst systems, then catalytic activity can be maintained, but stereosspecificity and hydrogen modulation sensitivity cannot be simultaneously optimized
Solution Approach 1:
The patent combines multiple electron donor compounds (internal electron donor in the solid catalyst component and external electron donor) with a twelve-membered ring compound cocatalyst to create a synergistic effect. This merging of multiple components resolves the contradiction by achieving both high stereosspecificity (through the internal electron donor and solid catalyst structure) and high hydrogen modulation sensitivity (through the external electron donor and twelve-membered ring cocatalyst), as demonstrated in the comparative examples where catalyst systems with multiple components outperformed those with single components.
Solution Approach 2:
The patent employs composite catalyst systems consisting of solid catalyst components (containing magnesium, titanium, and internal electron donor), external electron donors, and twelve-membered ring compounds as cocatalysts. This composite approach allows the system to integrate the advantages of different materials: the solid catalyst provides stereosspecificity, the external electron donor enhances hydrogen modulation sensitivity, and the twelve-membered ring cocatalyst boosts both catalytic activity and stereosspecificity, thereby resolving the technical contradiction.
2Manufacturing precision
If catalyst stereosspecificity is increased to improve isotactic index, then polymer quality improves, but catalytic activity and productivity may be compromised
Solution Approach 1:
The twelve-membered ring compound acts as an intermediary between the solid catalyst component and the external electron donor, mediating their interaction to achieve both high stereosspecificity and high catalytic activity. The specific structure of the twelve-membered ring compound (with oxygen atoms positioned to coordinate with titanium) enables it to enhance the stereosspecificity of the catalyst while simultaneously maintaining high catalytic activity, as shown in the examples where isotactic index reached 95-98% with activity exceeding 10000 g PP/g Cat·h.
Solution Approach 2:
The patent utilizes parameter changes in the catalyst system composition, specifically incorporating twelve-membered ring compounds with specific molecular structures (formula I) where R1-R6 can be various substituents. By changing the parameters of the electron donor compounds and cocatalysts, the system achieves optimal balance between stereosspecificity and catalytic activity, as demonstrated by the different examples showing activity ranging from 10000 to over 50000 g PP/g Cat·h with isotactic index above 95%.
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 catalyst system significantly improves stereospecificity and catalytic activity, resulting in polypropylene with high isotactic index and low ash content, while allowing for adjustable melt index through hydrogenation, making it suitable for high-strength and high-stereoregularity polypropylene production.
Implementation Method 1
by introducing a twelve-membered ring compound with a specific structure as a cocatalyst in the olefin polymerization process, and using it in conjunction with a Ziegler Natta-type main catalyst, the polymerization activity and stereosspecificity of the catalyst can be significantly improved
Implementation Method 2
catalyst system for olefin polymerization and use thereof
Data Source
AI summary
A catalyst system for olefin polymerization contains a main catalyst and a cocatalyst. The cocatalyst contains a twelve-membered ring compound represented by formula (M). The catalyst system is suitable for preparing polypropylene products having high stereoregularity and low ash, and can regulate the melt index of the products within a wide range by adjusting the amount of hydrogenation. It is also suitable for copolymerization systems to improve the copolymerization yield.