Solid Polymethylaluminoxane Catalyst Without Silica Support
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Solution Overview
Problem
Solid polymethylaluminoxane compositions used in olefin polymerization often result in poor morphology and reduced polymer bulk density, particularly when supported on silica, which also leads to reactor fouling and reduced activity compared to homogeneous polymerization.
Innovation Solution
A solid polymethylaluminoxane composition is developed with specific aluminum and Al2O3 content ranges, crystalline structure, and particle size distribution, which is prepared by adjusting heating conditions to enhance activity and morphology, eliminating the need for silica support and improving polymerization performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If silica support is used to prepare solid polymethylaluminoxane composition, then the composition can be handled in solid state, but the polymer morphology deteriorates and bulk density reduces
Solution Approach 1:
The invention extracts and eliminates the silica support component from the solid polymethylaluminoxane composition, retaining only the essential polymethylaluminoxane active species. This removal of the harmful support material resolves the contradiction by maintaining solid state handling capabilities while eliminating the negative impact on polymer morphology and bulk density that silica support causes.
Solution Approach 2:
The invention employs a support-free design where the polymethylaluminoxane itself serves as both the active catalyst component and the solid matrix. This disposable-like approach eliminates the need for permanent silica support structures, allowing the composition to function effectively in solid state without the morphological deterioration that traditional supports cause.
2Ease of operation
If silica support is used in solid polymethylaluminoxane composition, then solid state handling is enabled, but reactor fouling increases
Solution Approach 1:
The invention removes the silica support material that causes polymer adhesion and reactor fouling. By extracting this harmful component while maintaining the solid state structure through the polymethylaluminoxane itself, the composition enables solid state handling without generating the fouling problems associated with traditional silica-supported systems.
3Ease of operation
If silica support is used in solid polymethylaluminoxane composition, then solid form is achieved, but polymerization activity decreases compared to homogeneous polymerization
Solution Approach 1:
The invention uses the polymethylaluminoxane itself as a self-supporting solid structure, eliminating the need for external silica support that diminishes catalytic activity. This approach maintains the high polymerization activity characteristic of homogeneous systems while achieving solid form handling, as the active species are concentrated without dilution by inert support material.
Solution Approach 2:
The invention changes the structural parameters of the polymethylaluminoxane composition, specifically controlling the Al2O3 content (0.01-10 mol%) and aluminum content (36-43 mass%), to optimize the balance between solid state stability and catalytic activity. This parameter optimization enables the composition to function effectively in solid form while maintaining high polymerization productivity.
4Productivity
If Al2O3 content is increased in solid polymethylaluminoxane composition, then catalytic activity increases, but composition stability may be affected
Solution Approach 1:
The invention optimizes the Al2O3 content within a specific range (0.01-10 mol%) to achieve the desired balance between catalytic activity and composition stability. This controlled parameter adjustment allows the composition to exhibit enhanced activity while maintaining structural integrity and compositional stability during storage and polymerization processes.
Data Source
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AI summary
Provided is a solid polymethylaluminoxane composition which has higher activity when being used as a co-catalyst in olefin polymerization. The solid polymethylaluminoxane composition contains polymethylaluminoxane, trimethylaluminum, and Al2O3, wherein: (i) the aluminum content is in a range of 36-43 mass%; and (ii) the Al2O3 content is in a range of 0.001-10 mol% represented in terms of aluminum.