Magnesium Chloride Catalyst Component for Propylene Polymerization
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Solution Overview
Problem
Current polymerization catalyst systems for producing polyolefins, such as polypropylene, have limitations in activity and efficiency, leading to higher catalyst residue levels and increased production costs, while also being sensitive to ethylene in copolymerization processes.
Innovation Solution
A process involving the preparation of a polymerization catalyst component by contacting a Grignard compound with an alkoxy- or aryloxy-containing silane to form a solid magnesium compound, followed by treatment with an activating compound and a halogen-containing titanium compound in the presence of an inert dispersant, enhancing catalyst activity and reducing residue levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional Ziegler-Natta catalyst component is prepared using a 3-step process with magnesium-containing support and titanium tetrachloride, then the catalyst system achieves acceptable polyolefin production, but the activity is insufficient leading to higher catalyst residue levels and increased production costs
Solution Approach 1:
The patent applies preliminary action by pre-treating the magnesium-containing support with activating compounds (such as organometallic compounds, oxides, or hydroxides) before contacting with titanium tetrachloride. This pre-activation modifies the support surface properties in advance, creating more active sites for titanium deposition and resulting in higher catalyst activity that reduces catalyst residue in the final polymer product.
Solution Approach 2:
The patent changes the chemical parameters of the magnesium-containing support by introducing activating compounds that modify its surface composition and reactivity. This parameter change transforms the support from a passive carrier to an actively enhancing component, improving titanium dispersion and catalyst activity while reducing the amount of catalyst needed in the polymerization process.
2Productivity
If the catalyst activity is increased to reduce catalyst residue, then production costs decrease, but the ethylene sensitivity in copolymerization processes becomes more difficult to control
Solution Approach 1:
The patent applies local quality by creating non-uniform distribution of activating compounds on the magnesium support surface. Different regions of the catalyst component have different local compositions and activities, with some areas having higher activity for propylene polymerization while maintaining controlled sensitivity to ethylene. This local differentiation allows the catalyst to achieve high polyolefin yield while maintaining adaptability in copolymerization processes.
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 results in a catalyst system with higher activity, lower catalyst residues, and improved ethylene sensitivity, leading to increased polyolefin yield and reduced production costs, with favorable bulk density and particle size distribution in the polymer produced.
Implementation Method 1
contacting a compound R4zMgX2-z wherein R4 is an organic group, X is a halide, and z is larger than 0 and smaller than 2, with an alkoxy- or aryloxy-containing silane compound to give a solid magnesium-containing compound
Implementation Method 2
contacting the solid Mg(OR1)xCl2-x with at least one activating compound selected from the group formed by internal electron donors and compounds of formula M(OR2)v-w(R3)w in the presence of an inert dispersant to give an intermediate reaction product
Implementation Method 3
contacting the intermediate reaction product with a halogen-containing Ti-compound, optionally in the presence of an internal donor
Data Source
AI summary
The invention relates to a process for preparing a polymerization catalyst component wherein a solid compound with formula Mg(OR1)xCl2-x wherein x is larger than 0 and smaller than 2, and each R1, independently, represents an alkyl group, said compound being obtained by reacting a Grignard compound with an alkoxy- or aryloxy-containing silane compound, is contacted with at least one activating compound selected from the group formed by internal electron donors and compounds of formula M(OR2)v-w(R3)w, wherein M can be Ti, Zr, Hf, Al or Si, each R2 and R3, independently, represent an alkyl, alkenyl or aryl group, v is the valency of M and w is smaller than v, in the presence of an inert dispersant to give an intermediate reaction product, and wherein the intermediate reaction product is contacted with a halogen-containing Ti-compound. A catalyst system comprising said component shows improved performance in olefin polymerization.The invention also relates to a polymerization catalyst system comprising the catalyst component and to a process of making a polyolefin by contacting at least one olefin with a polymerization catalyst system comprising the catalyst component.