Metallocene Catalysts for Vinyl-Terminated Polyalphaolefins
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Solution Overview
Problem
Current catalyst systems struggle to produce high yields of vinyl-terminated polyalphaolefins (PAOs) when using C4+ olefin monomers, as they typically result in lower yields compared to C3-based monomers like propylene or ethylene.
Innovation Solution
A catalyst system comprising a Group 4 transition metal metallocene compound, specifically a bridged metallocene complex, combined with an activator such as alumoxane or a non-coordinating anion activator, is used to promote the polymerization of C3-C32 alpha olefins under specific conditions, achieving high yields of vinyl-terminated PAOs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional catalyst systems are used with C4+ olefin monomers, then polymerization reaction occurs, but vinyl-terminated PAO yield is low (typically below 60%)
Solution Approach 1:
The patent changes the chemical parameters of the catalyst system by introducing specific metallocene compounds with particular ligand structures (Formula I) and optimizing the activator type and catalyst-to-activator ratio. These parameter changes enable high vinyl-terminated PAO yields (≥60%) with C4+ olefin monomers, resolving the contradiction between productivity and reliability across different monomer types.
2Productivity
If ethylene or propylene co-monomers are added to achieve high vinyl termination, then vinyl-terminated oligomer yield increases, but process complexity and cost increase
Solution Approach 1:
The patent extracts and eliminates the need for ethylene or propylene co-monomers from the polymerization process. By using the specialized metallocene catalyst system with C4+ olefin monomers alone, the process achieves high vinyl-terminated PAO yields without the added complexity of co-monomer handling, blending, and process control.
Solution Approach 2:
The metallocene catalyst system acts as an intermediary that enables C4+ olefin monomers to directly produce high yields of vinyl-terminated PAOs without requiring ethylene or propylene co-monomers. The catalyst mediates the polymerization reaction to achieve the desired product characteristics from simpler feedstocks.
3Productivity
If 1-hexene is used as monomer, then polymerization occurs, but vinyl-terminated oligomer yield is only 35.9%
Solution Approach 1:
The patent changes the catalyst system parameters by employing specific metallocene compounds (Formula I) with defined ligand structures and activator combinations. This enables 1-hexene and other C4+ olefin monomers to produce vinyl-terminated oligomers at yields ≥60%, dramatically improving productivity while maintaining ease of manufacture by using single monomer feeds.
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 described catalyst system effectively generates vinyl-terminated PAOs with yields exceeding 60% even when using C4+ olefins, surpassing previous limitations and achieving high vinyl chain end percentages without the need for propylene co-monomers.
Implementation Method 1
a catalyst system comprising at least one activator and a metallocene compound represented by Formula (1)... contacting the catalyst system with an olefinic feed comprising a C3-C32 alpha olefin under polymerization reaction conditions
Data Source
AI summary
This invention relates to a method comprising contacting C3-C32 alpha olefin with catalyst system comprising activator and catalyst of the formula wherein: M is Hf or Zr; T is a bridging group; each X is independently a leaving group; R1 and R2 are independently hydrogen, or a Ci-Gto optionally substituted hydrocarbyl group, halide, or siloxyl group; R3, R4, R5 and R6 are independently a Ci-Gto optionally substituted hydrocarbyl, halocarbyl, silylcarbyl, aminocarbyl, or siloxyl group; and A is an aliphatic, aromatic or heteroaromatic ring, optionally bearing one or more additional fused rings which may be aliphatic, aromatic or heteroaromatic; obtaining a plurality of vinyl-terminated polyalphaolefins (PAOs) having at least 30 mol % vinyl terminated PAO's.