Titanium Zirconium Procatalyst Ligand Design for Ethylene Polymerization
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Solution Overview
Problem
Current catalyst systems for polyethylene and polypropylene polymerization do not adequately address the need for improved α-olefin response, specifically in terms of reactivity ratio, which affects the properties and applications of resulting polymers.
Innovation Solution
A procatalyst with a specific metal-ligand complex structure, comprising titanium, zirconium, or hafnium in a formal oxidation state of +2, +3, or +4, and a ligand system that includes monodentate or bidentate neutral, monoanionic, or dianionic ligands, along with specific hydrocarbylene or heterohydrocarbylene linkages, is used for the polymerization of ethylene and alpha-olefins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional catalyst systems are used for polyethylene polymerization, then the polymerization process can be carried out, but the α-olefin response and reactivity ratio are insufficient
Solution Approach 1:
The patent modifies the catalyst system by changing the ligand structure parameters - specifically using ligands with heteroatoms (O, S, N, P) and adjusted carbon chain lengths (C1-C40) to optimize the metal-ligand complex properties. This alters the electronic and steric parameters of the catalyst, improving α-olefin response and reactivity ratio while maintaining catalytic activity for polyethylene polymerization.
2Productivity
If existing catalyst systems are used, then polymerization can proceed, but the resulting polymers lack tailored properties for various applications
Solution Approach 1:
The patent introduces local quality modifications by incorporating specific heteroatom-containing groups (O, S, N, P) at particular positions in the ligand structure. These localized chemical modifications create specific electronic environments around the metal center, enabling tailored polymer properties while maintaining overall catalytic functionality for 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 procatalyst system enhances the polymerization process by improving the α-olefin response, leading to polymers with tailored properties suitable for various applications, thereby overcoming the limitations of existing catalyst systems.
Implementation Method 1
A procatalyst for the polymerization of ethylene and optionally one or more alpha-olefins... a polymerization process using the same... polymerizing ethylene and optionally one or more α-olefins in the presence of a catalyst system
Data Source
AI summary
The disclosure provides a procatalyst for the polymerization of ethylene and optionally one or more alpha-olefins having the structure shown in formula (I) below: wherein at least two of Y1-Y3 and at least two of Y4-Y6 are fluorine atoms and when only two of Y1- Y3 and only two of Y4-Y6 are fluorine atoms, the non-fluorine Y1-Y6 are selected from the group consisting of H atom, alkyl groups, aryl groups, heteroaryl groups, and alkoxy groups. Also provided is a polymerization process using the procatalyst.