Supported Metallocene Catalysts for Ethylene Polymerization
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Solution Overview
Problem
Current metallocene catalyst systems for ethylene homopolymerization and copolymerization require excessive aluminoxanes, leading to high production costs and undesirable polymer morphology, and lack efficient methods for producing high and ultra-high molecular weight polyethylenes with broad molecular weight distribution in slurry, bulk, and gas phase processes.
Innovation Solution
Development of supported metallocene catalysts based on transition metals of groups 4 or 5 with monocyclopentadienyl, monoindenyl, or monofluorenyl ligands, activated by non-aluminoxane organometallic compounds, using a process involving impregnation of silica with organometallic compounds and magnesium-based compounds, followed by reaction with transition metal complexes and optional halogenation, to produce high and ultra-high molecular weight ethylene homopolymers and copolymers with broad molecular weight distribution in various polymerization processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If aluminoxanes are used as activators in metallocene catalyst systems, then catalytic activity is improved, but production cost increases and polymer morphology becomes undesirable
Solution Approach 1:
The patent replaces expensive aluminoxane activators with cheaper organometallic compounds of groups 2 or 13 (such as alkyl aluminum compounds, alkyl magnesium compounds). These alternative activators achieve sufficient catalytic activity at lower costs, resolving the contradiction between productivity and manufacturing ease.
Solution Approach 2:
The patent changes the chemical parameters of the activator system by switching from aluminoxane-based chemistry to organometallic compounds with different metal centers (groups 2 or 13 elements). This parameter change maintains catalytic functionality while reducing cost and improving polymer morphology.
2Productivity
If aluminoxanes are used in metallocene catalyst systems, then catalytic activity is improved, but polymer morphology becomes poor and bulk density decreases
Solution Approach 1:
By substituting aluminoxanes with organometallic compounds of groups 2 or 13, the patent achieves better polymer morphology and higher bulk density while maintaining catalytic activity. The alternative activators promote more desirable polymer crystal structure and particle morphology.
Solution Approach 2:
The patent modifies the activator chemistry parameters to produce polymers with improved morphology. The organometallic compounds of groups 2 or 13 create different catalytic environments that favor better polymer crystal packing and morphology compared to aluminoxane-based systems.
3Ease of operation
If toluene is used as solvent in aluminoxane formulations, then catalyst formulation is enabled, but toxicological effects increase and storage stability decreases
Solution Approach 1:
The patent eliminates toluene and other aromatic solvents from the catalyst formulation by using alternative activators that do not require such solvents. This substitution removes the toxicological hazards and storage stability issues associated with toluene while maintaining catalyst functionality.
Solution Approach 2:
The patent changes the formulation parameters by replacing aluminoxane-toluene systems with organometallic compound systems that can be formulated in safer, non-aromatic solvents or without solvents, thereby eliminating toxicological effects and improving storage stability.
4Productivity
If conventional metallocene catalyst systems are used, then catalytic activity is achieved, but molecular weight distribution becomes narrow and high/ultra-high molecular weight polymers cannot be produced
Solution Approach 1:
The patent changes the catalyst system parameters by using metallocene catalysts with specific ligands (cyclopentadienyl, indenyl, or fluorenyl groups) combined with organometallic activators of groups 2 or 13. This parameter change enables production of high and ultra-high molecular weight polymers with broad molecular weight distribution, resolving the contradiction between catalytic activity and polymer molecular weight characteristics.
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 solution enables the production of high and ultra-high molecular weight ethylene polymers with controlled morphology and broad molecular weight distribution in slurry, bulk, and gas phase processes, reducing costs and improving polymer properties without the need for aluminoxanes, thus enhancing the efficiency and economic viability of the polymerization processes.
Implementation Method 1
impregnation of silica with organometallic compounds
Implementation Method 2
reaction with transition metal complexes
Implementation Method 3
supported metallocene catalysts... for the reaction of ethylene homopolymerization
Data Source
AI summary
The present invention relates a process for the preparation of catalytic support and the supported metallocene catalysts used in the production of ethylene homopolymers and ethylene copolymers with α-olefins, of high and ultra high molecular weight with broad molecular weight distribution, in gas or liquid phase polymerization processes, the latter being in slurry, bulk or suspension, and the products obtained from these processes.