Magnesium-Based Catalyst for LLDPE Copolymerization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing catalyst systems for producing linear low-density polyethylene (LLDPE) face challenges in achieving narrow molecular weight distribution, branching compositional distribution, and low density, while also experiencing issues with reactor fouling and poor powder flowability, which affect production efficiency and resin quality.
Innovation Solution
A magnesium-based catalyst system is developed through a process involving the formation of organic silicon complexes and their subsequent reaction with titanium compounds, followed by contact with a magnesium-based composite support, to create a catalyst component that is activated with a cocatalyst for ethylene and alpha-olefin copolymerization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If single site catalyst systems employing organometallic compounds and aluminoxane are used, then molecular weight distribution and branching compositional distribution are improved, but catalyst cost and process complexity increase due to immobilization requirements
Solution Approach 1:
The patent uses magnesium halide as an intermediary support material that simplifies the immobilization process. Unlike traditional silica or alumina supports requiring complex procedures, magnesium halide formed in-situ provides a straightforward platform for anchoring titanium catalysts, reducing process complexity while maintaining single-site catalyst performance
Solution Approach 2:
The patent employs magnesium halide, a cost-effective support material compared to expensive silica or alumina. The in-situ formation of magnesium halide from magnesium metal and halogenated hydrocarbons creates a disposable, easily prepared support that eliminates the need for complex immobilization processes while achieving the desired catalyst performance
2Productivity
If advanced Ziegler-Natta catalysts based on supported titanium systems are used, then production efficiency is improved, but molecular weight distribution and branching compositional distribution worsen
Solution Approach 1:
The patent creates locally uniform active sites on the magnesium halide support surface through controlled in-situ formation. The magnesium halide forms a consistent crystalline structure that provides uniform local environments for titanium catalysts, ensuring homogeneous active sites that produce narrow molecular weight distributions while maintaining high productivity
Solution Approach 2:
The patent changes the support material parameter from traditional silica or alumina to in-situ formed magnesium halide. This parameter change fundamentally alters the catalyst properties, enabling both high productivity and narrow molecular weight distribution by creating a support structure that promotes uniform active site formation and controlled polymerization
3Manufacturing precision
If catalysts are used to produce low density LLDPE, then resin quality is improved, but powder flowability and bulk density worsen due to resin stickiness and chunk formation
Solution Approach 1:
The patent performs preliminary pre-polymerization on the catalyst surface before actual polymerization. This preliminary action creates a protective polymer coating on catalyst particles that prevents resin stickiness and chunk formation during low density LLDPE production, maintaining good powder flowability while achieving the desired resin density
Solution Approach 2:
The patent applies pre-polymerization as a cushioning measure against the harmful effects of resin stickiness. By forming a preliminary polymer layer on catalyst particles, it cushions against the adhesion problems that would otherwise occur during low density LLDPE production, ensuring maintainable powder flowability
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 narrow molecular weight distribution, improved branching compositional distribution, and reduced lower molecular weight component content, while maintaining high bulk density and good powder flowability, thereby enhancing the production efficiency and quality of LLDPE.
Implementation Method 1
contacting the organic silicon complex (A) or the organic silicon complex containing nitrogen (B) with a compound having the formula Ti(OR6)aX4-a... thereby forming organic silicon complex (C)
Implementation Method 2
The catalyst component has been activated by contacting the catalyst component with cocatalyst
Data Source
AI summary
A high activity magnesium-based supported catalyst component useful in a catalyst system for the compolymerization of ethylene and alpha-olefin and a process for preparing the catalyst component is described. In the process, alkoxysilane ester is contacted with a halogen-substituted silane to form an organic silicon complex. Optionally, the organic silicon complex is contacted with an aminosilane compound to form an organic silicon complex containing nitrogen. The organic silicon complex containing nitrogen or the organic silicon complex is contacted with a transition metal compound to form an organic silicon complex containing transition metal. The organic silicon complex containing transition metal is then contacted with a substituted aromatic ring nitrogen compound to form a fourth reaction complex, which is then contacted with a magnesium-based composite support that has been prepared in situ by reacting metallic magnesium with an alkyl or aromatic halide to form the catalyst component.