Chloride-Deficient Magnesium Chloride Catalyst Preparation
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Solution Overview
Problem
Existing magnesium chloride supported Ziegler-Natta catalysts face performance issues due to un-reacted dialkylmagnesium species, which require time-consuming filtration and washing steps, making them unsuitable for in-line catalyst preparation and increasing production costs.
Innovation Solution
A split chloride addition method is employed, where a sub-stoichiometric amount of chloride ion is added in two distinct steps to form a chloride-deficient magnesium chloride support, reducing the amount of un-reacted dialkylmagnesium and eliminating the need for filtration steps, allowing for direct use in olefin polymerization without isolating catalyst components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If filtration and washing steps are used to remove un-reacted dialkylmagnesium species, then catalyst performance is improved, but production time and cost increase
Solution Approach 1:
The patent applies preliminary action by adding chloride ion in two distinct steps to prevent the formation of un-reacted dialkylmagnesium species from the outset. In the first step, sub-stoichiometric chloride is added to form chloride-deficient magnesium chloride support. In the second step, additional chloride is added to react with any remaining dialkylmagnesium species, thereby preliminarily eliminating the need for subsequent filtration and washing steps while maintaining catalyst performance.
2Reliability
If filtration and washing steps are used to remove un-reacted dialkylmagnesium species, then catalyst performance is improved, but production cost increases
Solution Approach 1:
The patent eliminates the need for expensive filtration and washing operations by implementing preliminary chloride addition in two steps. The first step forms the magnesium chloride support structure, while the second step ensures complete reaction of dialkylmagnesium species, thereby preventing costly post-processing operations while maintaining high catalyst activity.
3Reliability
If electron donor compounds are used to prepare magnesium chloride support, then catalyst effectiveness is improved, but procedural steps and cost increase
Solution Approach 1:
The patent changes the chemical parameters of the magnesium chloride support by controlling the chloride-to-magnesium ratio through two-step addition. The first step creates chloride-deficient support (ratio < 2:1), and the second step adjusts the ratio to optimize catalyst effectiveness without requiring electron donor compounds, thereby simplifying the procedure while maintaining performance.
4Reliability
If chloride ion is added in sub-stoichiometric amounts to form chloride-deficient magnesium chloride support, then un-reacted dialkylmagnesium is reduced, but complete chloride reaction may not be achieved
Solution Approach 1:
The patent segments the chloride addition process into two distinct steps. The first step adds sub-stoichiometric chloride to form chloride-deficient magnesium chloride support, creating the desired catalyst structure. The second step adds additional chloride to react with any remaining dialkylmagnesium species, ensuring complete reaction while maintaining the chloride-deficient characteristic necessary for high catalyst activity.
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
This method produces high-activity Ziegler-Natta catalysts suitable for in-line applications, reducing production costs and time, while maintaining catalyst performance without the need for electron donor compounds.
Implementation Method 1
combining a diorganomagnesium compound with less than 2 molar equivalents of chloride provided by a first source of chloride to produce a 'chloride deficient' magnesium chloride support
Implementation Method 2
adding a second source of chloride which reduces the amount of soluble un-reacted diorganomagnesium compound present
Data Source
AI summary
An olefin polymerization catalyst is prepared by (a) in a diluent, combining a diorganomagnesium compound with less than 2 molar equivalents of a first source of chloride to produce a “chloride deficient” magnesium chloride support; (b) without isolating any solids, adding a second source of chloride which reduces the amount of soluble un-reacted diorganomagnesium compound present; (c) without isolating any solids present, adding a tetravalent titanium species and; (d) adding an activator. The catalyst is active for solution polymerization of olefins.