Mixed Catalyst System for Ethylene Copolymerization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing mixed catalyst systems comprising Ziegler catalysts and tridentate iron or cobalt catalysts produce ethylene copolymers with low comonomer incorporation in the high molecular weight fraction, which is undesirable for achieving good physical properties.
Innovation Solution
A process for manufacturing a mixed catalyst system by combining a Ziegler catalyst with a tridentate iron complex on a granular support, where the tridentate iron complex is synthesized in an organic solvent with less than 1% electron donor compounds, and the reaction involves an iron halogenide added to a ligand solution in a non-polar solvent, without using additional electron donor ligands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If tridentate iron catalysts are manufactured using conventional methods in polar organic solvents (THF, n-butanol), then the catalyst system can be produced, but the comonomer incorporation in the high molecular weight polymer fraction remains low
Solution Approach 1:
The patent changes the solvent parameter from polar organic solvents (THF, n-butanol) to non-polar hydrocarbon solvents (heptane, toluene). This parameter change fundamentally alters the catalyst's interaction with comonomers, enabling significant comonomer incorporation even in the high molecular weight fraction while maintaining ease of manufacture through standard industrial solvents.
Solution Approach 2:
The patent introduces local quality differences in the catalyst system by creating distinct catalyst environments through solvent selection. The non-polar solvent environment creates specific local conditions around the iron catalyst that favor comonomer incorporation, while the Ziegler catalyst maintains its conventional behavior, thus achieving differentiated polymer fractions with different comonomer contents.
2Strength
If conventional catalyst systems are used, then the manufacturing process is simple, but the physical properties of the copolymer (abrasion and stress cracking resistance) are poor
Solution Approach 1:
The patent employs a composite catalyst system combining Ziegler catalyst and tridentate iron catalyst, where each catalyst contributes different properties to the final copolymer. The Ziegler catalyst produces the high molecular weight fraction while the iron catalyst enables comonomer incorporation, creating a composite material with both high strength and good physical properties.
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 resulting copolymers exhibit a broad molecular weight distribution and significant comonomer incorporation even in the high molecular weight fraction, improving their physical properties such as abrasion and stress cracking resistance.
Implementation Method 1
the reaction involves an iron halogenide added to a ligand solution in a non-polar solvent
Implementation Method 2
mixed catalyst system comprising a Ziegler catalyst and a tridentate iron catalysts... for the copolymerization of ethylene with c1-c12 alpha-olefins
Data Source
Figure 1
AI summary
A novel process for the manufacture of a mixed catalyst system by combining a Ziegler catalyst and a tridentate iron complex is described, which is characterized in that the reaction of a tridentate ligand with an iron compound is performed in an organic solvent containing less than 10 percent by weight, based on the total amount of the organic solvent, of electron donor compounds selected from the group consisting of ethers, aliphatic esters, aromatic esters, tertiary amines, amides, silanes, silazanes or orthoesters.