Metallocene Catalyst System for High Temperature Solution Polymerization
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Solution Overview
Problem
Existing catalyst systems for high temperature solution polymerization of ethylene copolymers have low productivity and activity, necessitating the development of new catalyst systems that can produce ethylene copolymers with desired properties at high temperatures.
Innovation Solution
A catalyst system comprising a metallocene complex of specific formula, an aluminoxane cocatalyst, and a boron-containing cocatalyst is used in a high temperature solution polymerization process to enhance productivity and comonomer incorporation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional metallocene catalyst systems are used in high temperature solution polymerization, then ethylene copolymers can be produced, but the productivity and activity remain relatively low
Solution Approach 1:
The patent combines a metallocene complex with a dual cocatalyst system comprising both aluminoxane and boron-based cocatalysts. This merging of multiple catalytic components creates a synergistic effect that dramatically enhances both productivity and catalyst activity compared to conventional single cocatalyst systems. The metallocene complex (i) is combined with aluminoxane cocatalyst (ii) and boron-based cocatalyst (iii) to form an integrated catalytic system that resolves the contradiction between productivity and reliability.
Solution Approach 2:
The catalyst system represents a composite catalytic material combining organometallic metallocene complex with two types of cocatalysts (aluminoxane and boron-based). This composite approach creates a multifunctional catalyst system where each component contributes specific properties: the metallocene provides stereoselectivity and activity, aluminoxane provides cocatalytic activation, and boron-based cocatalyst enhances stability and productivity. This composite structure enables high temperature solution polymerization with improved performance.
2Productivity
If high temperature solution polymerization is used, then process efficiency is improved, but catalyst activity and productivity decrease
Solution Approach 1:
The patent utilizes parameter changes by optimizing the structural parameters of the metallocene complex (specific substitution patterns at positions 2 and 4 of both indenyl rings) and the composition parameters of the cocatalyst system (aluminoxane and boron-based cocatalyst combination). These parameter optimizations enable the catalyst to maintain high activity and productivity at elevated temperatures (above 100°C), resolving the contradiction between temperature and productivity. The specific structural parameters of the metallocene ligands are tuned to enhance thermal stability while maintaining catalytic 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 excellent productivity, comonomer incorporation, and thermal stability, producing ethylene copolymers with improved properties suitable for various applications.
Implementation Method 1
a catalyst system comprising (i) a metallocene complex of formula (I)... These combinations remarkably give rise to catalyst systems with excellent activity, productivity and stability
Implementation Method 2
a cocatalyst mixture comprising an aluminoxane cocatalyst and a boron based cocatalyst. These combinations remarkably give rise to catalyst systems with excellent activity, productivity and stability
Data Source
AI summary
Catalyst system for producing ethylene copolymers in a high temperature solution process, the catalyst system comprising (i) a metallocene complex of formula (I) wherein M is Hf or Zr X is a sigma ligand, L is a bridge of the formula -SiR82-, wherein each R8 is independently a C1-C20-hydrocarbyl, tri(C1-C20-alkyl)silyl, C6-C20-aryl, C7-C20-arylalkyl or C7-C20-alkylaryl n is 0, 1 or 2 R1 and R1' are the same or can be different and can be a linear or branched C1-C6-alkyl group, R2 and R2' are the same or are different and are a CH2-R9 group, with R9 being H or linear or branched C1-C6-alkyl group R5 and R5' are the same or are different and can be H or a linear or branched C1-C6-alkyl group or a OR group, wherein R is a C1-C6-alkyl group R6 and R6' are the same or are different and can be H or a C(R10)3 group, with R10 being the same or different and R10 can be H or a linear or branched C1-C6-alkyl group or R5 and R6 and/or R5' and R6' taken together form an unsubstituted 4-7 membered ring condensed to the benzene ring of the indenyl moiety, and R7 and R7' can be the same or are different and can be H or a linear or branched C1-C6-alkyl group (ii) an aluminoxane cocatalyst and (iii) a boron containing cocatalyst