Hybrid Metallocene Catalysts for Broad Polyolefin Molecular Weight
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Solution Overview
Problem
Current catalyst systems struggle to produce polyolefins with a broad molecular weight distribution and low long chain branching, as metallocene and Ziegler-type catalysts either produce polyolefins with too narrow a distribution or excessive long chain branching, while chromium-based systems are difficult to replicate.
Innovation Solution
Development of novel hybrid metallocene compounds with a heteroatom-containing ligand bound to the transition metal, used in catalyst compositions that include an activator such as an organoaluminum compound, aluminoxane, or ionizing ionic compound, to achieve specific polymerization outcomes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If metallocene catalysts are used, then molecular weight distribution becomes narrow, but the patent requires broad molecular weight distribution
Solution Approach 1:
The patent combines a metallocene component with a chromium component in a single catalyst system. The metallocene provides controlled polymerization activity while the chromium component contributes to broader molecular weight distribution and reduced long chain branching, achieving properties that neither component could produce alone
Solution Approach 2:
The catalyst system uses a composite structure consisting of a metallocene compound supported on a chromium-containing support material. This composite catalyst integrates the benefits of both metallocene and chromium catalysts, producing polyolefins with broad molecular weight distribution and low long chain branching
2Manufacturing precision
If Ziegler-type catalyst systems are used, then molecular weight distribution becomes narrow and long chain branching is reduced, but the patent requires broad molecular weight distribution
Solution Approach 1:
The patent combines a metallocene component with a chromium component in a single catalyst system. The metallocene provides controlled polymerization activity while the chromium component contributes to broader molecular weight distribution and reduced long chain branching, achieving properties that neither component could produce alone
Solution Approach 2:
The catalyst system uses a composite structure consisting of a metallocene compound supported on a chromium-containing support material. This composite catalyst integrates the benefits of both metallocene and chromium catalysts, producing polyolefins with broad molecular weight distribution and low long chain branching
3Adaptability or versatility
If chromium-based catalyst systems are used, then broad molecular weight distribution and low long chain branching are achieved, but the patent requires a non-chromium alternative
Solution Approach 1:
The patent extracts the beneficial polymerization properties from chromium-based catalysts (broad molecular weight distribution and low long chain branching) and transfers them to a non-chromium catalyst system using metallocene and alternative activators, eliminating chromium while preserving desired product properties
Solution Approach 2:
The patent changes the chemical composition parameters of the catalyst system by replacing chromium with alternative activators such as aluminoxanes or organoboron compounds, while adjusting other catalyst components to achieve the same polymerization outcomes without chromium
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
These catalyst compositions effectively produce polyolefins with a broad molecular weight distribution and low long chain branching, matching the properties of chromium-based systems without using chromium, thereby offering a non-chromium alternative.
Implementation Method 1
Catalyst compositions containing a hybrid metallocene compound and an activator can be used to produce, for example, ethylene-based homopolymers and copolymers
Data Source
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AI summary
The present invention provides polymerization catalyst compositions employing half-metallocene compounds with a heteroatom-containing ligand bound to the transition metal. Methods for making these hybrid metallocene compounds and for using such compounds in catalyst compositions for the polymerization of olefins also are provided.