Solid PMAO Composition Production for Polymerization
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Solution Overview
Problem
The challenge is to develop a solid poly-methylaluminoxane (PMAO) composition with a relatively large particle diameter that maintains high activity under severe reaction conditions, similar to those in actual olefin polymerization processes, while avoiding the issues of polymer fouling and decreased activity associated with supported solid PMAO compositions.
Innovation Solution
A method involving the preparation of a solid PMAO composition by heating an aromatic hydrocarbon solution containing poly-methylaluminoxane and trimethylaluminum, followed by additional precipitation steps to achieve a larger median diameter and uniform particle size distribution, ensuring high polymerization activity and preventing fouling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a supported solid PMAO composition is used, then polymer fouling is prevented and handling is improved, but polymerization activity decreases significantly
Solution Approach 1:
The invention extracts the support material (silica, alumina, etc.) from the solid PMAO composition, retaining only the active PMAO component in solid particle form. This extraction eliminates the deactivating effect of supports while preserving the solid state benefits for polymer handling and fouling prevention.
Solution Approach 2:
The invention changes the physical state parameter of PMAO from liquid/dissolved to solid particle form, and controls particle size parameters (median diameter 5-50 μm) to achieve both high activity and good handling properties without requiring support materials.
2Shape
If a supported solid PMAO composition is used, then polymer morphology control is improved, but polymerization activity decreases
Solution Approach 1:
The invention removes the support component from traditional supported solid PMAO compositions, using pure PMAO particles instead. This eliminates the support-induced activity decrease while maintaining the ability to control polymer morphology through solid particle effects.
Solution Approach 2:
The solid PMAO composition serves multiple functions simultaneously: it acts as a co-catalyst activator, provides polymer morphology control through its solid particle effect, and prevents polymer fouling, all without requiring support materials that would reduce activity.
3Productivity
If liquid PMAO composition is used, then polymerization activity is high, but polymer morphology control is lost and fouling occurs
Solution Approach 1:
The invention utilizes the phase transition of PMAO from liquid/dissolved state to solid particle state. This phase change enables the PMAO to exert morphological control effects on the polymer while maintaining high co-catalyst activity, and prevents polymer fouling by eliminating the continuous liquid phase that causes adhesion.
4Length of moving object
If silica support is used, then solid PMAO composition is formed, but fish eyes appear in polymer films and activity decreases
Solution Approach 1:
The invention extracts and eliminates the silica support component that causes fish eyes and activity decrease, using pure PMAO particles instead. This removal of the harmful support material eliminates fish eye formation while maintaining high polymerization activity.
Solution Approach 2:
The invention converts the traditionally harmful role of support materials into a benefit by eliminating them entirely, using the PMAO itself in solid particle form to provide both the co-catalyst function and the morphological control that would otherwise require a support.
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 resulting solid PMAO composition exhibits high activity and uniform particle size, effectively preventing fouling and maintaining polymer quality under severe conditions, thus addressing the limitations of existing supported solid PMAO compositions.
Implementation Method 1
heating an aromatic hydrocarbon solution containing poly-methylaluminoxane and trimethylaluminum to precipitate a solid PMAO composition
Implementation Method 2
precipitation steps to achieve a larger median diameter and uniform particle size distribution
Data Source
AI summary
A method for producing a high-activity solid PMAO composition is provided, involving: (a) heating an aromatic hydrocarbon solution of TMAL and PMAO containing units having formula (I), and precipitating a solid PMAO composition containing PMAO and TMAL; (b) adding an aromatic hydrocarbon solution of TMAL and PMAO containing units represented by formula (I) to a solution containing the solid PMAO composition; and (c) heating the resulting solution, thereby precipitating a solid PMAO composition. In steps (b) and (c), at least 70% of the PMAO and TMAL in terms of aluminum precipitates. The median diameter d2 of the solid PMAO composition produced in (c) is greater than the median diameter d1 of the solid PMAO composition produced in (a).-[(Me)AlO]n— (I)In formula (I), n represents an integer of 10-50. An olefin polymerization catalyst using the solid PMAO composition and a method for producing an olefin polymer using this catalyst are also described.