Tridentate Nitrogen Ligands for Broad Molecular Weight Polyethylene
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Solution Overview
Problem
There is a need for controlled techniques to produce polyethylene copolymers with broad molecular weight distributions to achieve improved physical properties such as stiffness, toughness, and environmental stress crack resistance, which are essential for commercially desirable products, but existing catalyst systems often narrow the molecular weight distribution as temperature increases, limiting production rates and uniform comonomer incorporation.
Innovation Solution
A method involving the reaction of a bromoketone compound with an aryl amine to form an amide, followed by reaction with an ethylene diamine to create a terminal primary amine, and then with a bromoaryl compound to form a ligand, which is subsequently reacted with a metal compound to form a non-metallocene catalyst precursor, allowing for the production of polyethylene with controlled molecular weight distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If single site catalysts are used to increase production rates by raising temperature, then productivity improves, but molecular weight distribution narrows
Solution Approach 1:
The invention divides the catalytic system into multiple independent catalyst sites within a single reactor, each capable of producing polymers with different molecular weight distributions. This segmentation allows the system to maintain broad overall MWD while operating at high temperatures for high productivity, resolving the contradiction between production rate and MWD breadth.
Solution Approach 2:
The invention creates a composite catalyst system combining different types of catalysts (e.g., metallocene and non-metallocene catalysts) with different catalytic characteristics. This composite approach enables simultaneous production of polymer fractions with varying molecular weights, achieving broad MWD at high production rates without sacrificing composition stability.
2Stability of the object's composition
If traditional Ziegler-Natta catalysts are used to achieve broad molecular weight distribution, then molecular weight distribution broadens, but manufacturing precision deteriorates
Solution Approach 1:
The invention assigns different local qualities to different catalyst sites, where each site has specific catalytic properties optimized for producing particular polymer characteristics. This allows precise control over comonomer incorporation at each site while collectively achieving broad MWD, thereby maintaining both composition stability and manufacturing precision.
Solution Approach 2:
The invention systematically varies key parameters (catalyst structure, ligand types, metal centers) across different catalyst sites to create a distribution of catalytic activities. This parameter optimization enables each site to produce polymers with controlled MWD and comonomer incorporation, achieving both broad overall MWD and high manufacturing precision.
3Stability of the object's composition
If two-reactor systems are used to produce bimodal polymers with broad MWD, then molecular weight distribution broadens, but device complexity increases
Solution Approach 1:
The invention merges the functions of multiple reactors into a single reactor by incorporating multiple catalyst sites with different characteristics within one system. This consolidation achieves bimodal/broad MWD production while eliminating the complexity of multi-reactor configurations, reducing capital costs and operational complexity.
Solution Approach 2:
The single reactor system is designed with universal capability to support multiple catalyst types and produce polymers with different MWD characteristics simultaneously. This multi-functional approach replaces the need for specialized reactors for different polymer fractions, simplifying the overall device configuration while maintaining broad MWD production capability.
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 approach enables the production of polyethylene with a broad molecular weight distribution, enhancing physical properties like stiffness and toughness while maintaining production efficiency, by using a non-metallocene catalyst system that avoids traditional toxic nitrogenous building blocks and allows for scalable processes.
Implementation Method 1
reacting a bromoketone compound with an aryl amine compound to form an amide compound
Implementation Method 2
The amide compound is reacted with an ethylene diamine compound, to form a terminal primary amine compound
Implementation Method 3
The terminal primary amine compound is reacted with a bromoaryl compound to form a ligand
Implementation Method 4
The ligand is reacted with a metal compound to form a catalyst precursor
Implementation Method 5
the catalyst precursor is activated to form an active catalyst
Implementation Method 6
The catalyst is reacted with at least ethylene to form a polymer
Data Source
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AI summary
Catalyst systems and methods for making and using the same are provided. A method for forming a polymer catalyst includes reacting a bromoketone compound with an aryl amine compound to form an amide compound. The amide compound is reacted with an ethylene diamine compound, to form a terminal primary amine compound. The terminal primary amine compound is reacted with a bromoaryl compound to form a ligand.