Aluminum Alkoxide Activator for Metallocene Polymerization
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Solution Overview
Problem
The polyolefin industry faces challenges with the high cost and batch-to-batch variability of methylalumoxane (MAO) as a catalyst activator for metallocene catalysts, and the complexity of using Lewis acidic boranes in polymerization processes due to fast kinetics, leading to polymer morphology issues and reactor fouling.
Innovation Solution
A method involving the combination of compounds with active hydrogen moieties and fluorine substituents with trialkylaluminum compounds to create activator compositions for olefin polymerization, which can be supported on materials like silica or alumina, providing a cost-effective and consistent catalyst system with improved productivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If methylalumoxane (MAO) is used as a catalyst activator for metallocene catalysts, then high catalytic activity is achieved, but the cost increases and batch-to-batch variability occurs
Solution Approach 1:
The patent replaces expensive MAO with cheaper aluminum compounds such as aluminum triisopropoxide or aluminum triethyl that can be readily prepared and handled. These alternative activators achieve comparable catalytic activity without the high cost and batch variability associated with MAO, effectively substituting an expensive material with a more economical one.
Solution Approach 2:
The patent modifies the chemical parameters of the activator by using different aluminum compounds with varying alkoxide or alkyl groups. This parameter change allows optimization of both cost and performance, achieving consistent batch-to-batch results while maintaining high catalytic activity through controlled reaction conditions.
2Reliability
If Lewis acidic boranes are used as activators with metallocenes, then catalytic activity is improved, but polymer morphology issues and reactor fouling occur due to fast polymerization kinetics
Solution Approach 1:
The patent introduces aluminum compounds as intermediary activators that mediate between the metallocene catalyst and the olefin substrate. These intermediaries provide controlled activation that prevents the excessively fast kinetics caused by direct borane-catalyst interaction, thereby avoiding polymer morphology defects and reactor fouling while maintaining high catalytic activity.
Solution Approach 2:
The patent uses aluminum compounds that provide partial activation of the metallocene catalyst compared to the full activation achieved with boranes. This partial action is sufficient to achieve high catalytic activity but prevents the excessive reaction rate that leads to polymerization control issues and reactor fouling.
3Productivity
If traditional catalyst systems are used, then polymerization activity is maintained, but batch variability and handling complexity increase
Solution Approach 1:
The patent employs aluminum compounds such as aluminum triisopropoxide that can be readily prepared from commercially available materials and that self-activate metallocene catalysts without requiring complex preparation procedures. This self-service capability simplifies handling and eliminates the need for specialized equipment or procedures, making the process easier to operate while maintaining high productivity.
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 proposed solution offers a cost-effective and easily preparable activator system that maintains high activity in olefin polymerization, reducing the issues of batch variability and reactor fouling associated with traditional catalysts, while ensuring good productivity and polymer morphology.
Implementation Method 1
combining at least one compound comprising at least one active hydrogen moiety and at least one fluorine substituent with water
Implementation Method 2
adding at least one compound comprising at least one aluminum alkyl moiety; wherein the at least one compound comprising at least one aluminum alkyl moiety is a trialkylaluminum
Data Source
Figure 1
AI summary
Catalyst activators and methods for their preparation and their use in processes for polymerizing olefins are described. In particular, catalyst activators derived from aluminum alkyls and their use with metallocene type catalyst systems and/or conventional-type transition metal catalyst systems are described.