Olefin Procatalyst Chloride Ethoxide Control
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Solution Overview
Problem
Existing catalyst systems for olefin polymerization, such as Ziegler-Natta catalysts, face challenges in achieving high isotacticity and low xylene solubles content in polyolefins due to limitations in controlling chloride and ethoxide content, which affect the porosity and titanium anchoring in the catalyst support.
Innovation Solution
A procatalyst is developed using a magnesium support prepared by combining alkyl magnesium and Grignard reagents, with the addition of tetrahalogensilane to adjust chloride and ethoxide content, allowing for more control over polymerization and resulting in higher isotacticity and lower xylene solubles content polyolefins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If only Grignard reagent is used for magnesium support preparation (prior art method), then the process is simpler, but the control over chloride and ethoxide content is insufficient, resulting in lower isotacticity and higher xylene solubles content
Solution Approach 1:
The magnesium support preparation process is segmented into multiple stages: first forming the magnesium support with Grignard reagent, then separately adjusting chloride content with tetrahalogensilane and ethoxide content with alkyl magnesium compound. This segmentation allows independent control of each compositional parameter, resolving the contradiction between manufacturing precision and process complexity.
Solution Approach 2:
The invention changes the chemical composition parameters of the magnesium support by introducing tetrahalogensilane to adjust chloride content and alkyl magnesium compound to adjust ethoxide content. These parameter changes enable precise control over the catalyst's isotacticity and xylene solubles content, transforming the preparation from a simple single-reagent process to a multi-parameter controlled process.
2Manufacturing precision
If alkyl magnesium and Grignard reagents are combined with tetrahalogensilane, then chloride and ethoxide content can be precisely controlled, but the process complexity increases
Solution Approach 1:
The magnesium support serves multiple functions: it provides the base structure for catalyst anchoring, acts as a chloride source through tetrahalogensilane treatment, and serves as an ethoxide source through alkyl magnesium compound addition. This multi-functionality of the magnesium support reduces the need for separate components, partially offsetting the increased process complexity with improved manufacturing precision.
3Manufacturing precision
If higher amounts of alkyl magnesium are used, then chloride content increases and ethoxide content decreases, but the process requires more precise ratio control
Solution Approach 1:
The invention establishes a feedback relationship between the amounts of alkyl magnesium and Grignard reagents used and the resulting chloride and ethoxide content in the magnesium support. By monitoring and adjusting the molar ratios of these reagents, operators can control the final compositional parameters, transforming ratio adjustment from a trial-and-error process to a controlled feedback-driven process.
4Manufacturing precision
If higher amounts of tetrahalogensilane are used, then ethoxide content decreases and titanium anchoring decreases, but the process requires precise dosing control
Solution Approach 1:
The invention performs preliminary action by pre-calculating and pre-mixing the tetrahalogensilane with the magnesium support before titanium anchoring occurs. This preliminary treatment establishes the desired ethoxide content and chloride content in the magnesium support, ensuring that subsequent titanium anchoring occurs on a pre-optimized substrate, thereby reducing the need for precise dosing during the titanium addition step.
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 process produces polyolefins with improved isotacticity and reduced xylene solubles content, achieving higher bulk density and polymer yield while maintaining the morphology and particle size distribution of the catalyst support.
Implementation Method 1
contacting a compound R4MX (where M is magnesium, X is a halide and R is an alkyl or aryl group) with a Grignard reagent R4MgX
Implementation Method 2
the solid support is precipitated with the use of a tetrahalogensilane, preferably tetrachlorosilane
Data Source
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AI summary
The invention relates to a procatalyst for polymerization of olefins. The invention also relates to a process for preparing said procatalyst. Furthermore, the invention is directed to a catalyst system for polymerization of olefins comprising the said procatalyst, a co-catalyst and optionally an external electron donor; a process of preparing polyolefins by contacting an olefin with said catalyst system and to polyolefins obtained or obtainable by said process. The invention also relates to the use of said procatalyst in the polymerization of olefins.