Composite Catalyst for High-Molecular-Weight Ethylene Polymerization
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Solution Overview
Problem
Existing catalyst systems struggle to produce high molecular weight polymers at high polymerization temperatures (120° C to 250° C) with high efficiency and reactivity.
Innovation Solution
A catalyst system comprising a heterogeneous procatalyst with a titanium species, an aluminum species, and a magnesium chloride component, combined with a hydrogenation procatalyst of the formula Cp2TiX2, where each Cp is a cyclopentadienyl substituted with (C1-C10)alkyl and each X is a halogen atom.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional catalyst systems are used at high polymerization temperatures (120°C to 250°C), then polymerization reaction rate is maintained, but molecular weight of the produced polymer decreases
Solution Approach 1:
The patent employs a composite catalyst system combining Ziegler-Natta catalyst components (titanium species on magnesium chloride support with aluminum alkyl co-catalyst) and metallocene hydrogenation catalyst (Cp2TiX2). This composite approach allows the Ziegler-Natta component to produce high molecular weight polymer at elevated temperatures while the metallocene component simultaneously removes hydrogen to maintain high molecular weight, resolving the contradiction between temperature and molecular weight
2Productivity
If high polymerization temperatures (120°C to 250°C) are used to increase productivity, then production rate improves, but polymer molecular weight and quality deteriorate
Solution Approach 1:
The patent changes the chemical parameters of the catalyst system by introducing the metallocene hydrogenation catalyst Cp2TiX2 with specific structural features (cyclopentadienyl ligands with alkyl substituents and halogen atoms). This parameter change enables the catalyst to function effectively at high temperatures (120-250°C) while maintaining molecular weight above 100,000 g/mol, thus improving productivity without sacrificing polymer quality
3Quantity of substance
If conventional Ziegler-Natta catalysts are used alone, then polymerization efficiency is moderate, but molecular weight exceeds 100,000 g/mol cannot be achieved at high temperatures
Solution Approach 1:
The patent merges two catalyst functionalities into one system: the Ziegler-Natta catalyst for polymerization and the metallocene hydrogenation catalyst for hydrogen removal. This merging allows the system to achieve both high molecular weight (>100,000 g/mol) and high polymerization efficiency at temperatures of 120-250°C, as the hydrogenation component prevents molecular weight degradation while the polymerization component maintains high activity
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 achieves high molecular weight polymer production (greater than 100,000 g/mol) at elevated temperatures with enhanced efficiency and reactivity, suitable for various polymer applications.
Implementation Method 1
a heterogeneous procatalyst and a hydrogenation procatalyst. The heterogeneous procatalyst includes a titanium species, an aluminum species, and a magnesium chloride component
Implementation Method 2
Titanocene hydrogenation catalysts have been used in (1) metallocene-catalyzed polymerization reactions, for removing H2 generated by the metallocene polymerization catalysts
Data Source
AI summary
The catalyst system includes a heterogeneous procatalyst and a hydrogenation procatalyst. The heterogeneous procatalyst includes a titanium species, an aluminum species, and a magnesium chloride component. The hydrogenation procatalyst has the formula Cp2TiX2, In formula Cp2TiX2, each Cp is a cyclopentadienyl substituted with at least one R1, wherein R1 is (C1-C10)alkyl; and each X is independently a halogen atom.