Olefin Polymerization Catalyst Component High Temperature Activity
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Solution Overview
Problem
Existing Ziegler-Natta catalysts face challenges in achieving uniform distribution of active components, leading to inhomogeneous polymer materials and reduced activity at higher temperatures, due to difficulties in controlling the precipitation step and morphology of catalyst particles.
Innovation Solution
A process involving a liquid/liquid two-phase system where a Group 2 metal complex is formed with an electron donor, then emulsified with a transition metal compound, and solidified, with the addition of an aluminium alkyl compound to shift the catalyst activity maximum to higher temperatures without compromising morphology.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a supported ZN catalyst system is prepared by impregnating catalyst components on a particulate support material, then the catalyst can be formed with defined support structure, but the surface treatment may lead to non-uniform distribution of active components and inhomogeneous polymer material
Solution Approach 1:
The invention extracts the support material from the catalyst preparation process entirely. Instead of using external supports like silica or MgCl2 that require impregnation, the catalyst components themselves (Mg compound and transition metal compound) form the particulate structure directly through precipitation from solution, eliminating the impregnation step and its associated non-uniformity problems
Solution Approach 2:
The invention performs preliminary action by pre-forming the catalyst components in solution with controlled composition and distribution before the precipitation step. The Mg compound and transition metal compound are dissolved and mixed in specific ratios and conditions, ensuring uniform distribution is established before the catalyst particles form, rather than attempting to achieve uniformity during or after impregnation
2Manufacturing precision
If precipitation methods are used to form solid ZN catalyst, then catalyst particles can be obtained, but the precipitation step is difficult to control and morphology of catalyst particles cannot be precisely controlled
Solution Approach 1:
The invention applies parameter changes by carefully controlling solution conditions including temperature (0-50°C), solvent composition (hydrocarbon mixtures), pH, and concentration ratios of Mg compound to transition metal compound. These parameter optimizations control the precipitation kinetics to produce catalyst particles with desired morphology and size distribution, making the process predictable and controllable
Solution Approach 2:
The invention incorporates feedback mechanisms by monitoring and adjusting precipitation conditions based on observed particle formation. The process allows for control of supersaturation levels and precipitation rate to prevent tar-like intermediate formation and ensure uniform particle morphology, with adjustments made during the precipitation step based on process conditions
3Temperature
If conventional ZN catalysts are used, then catalyst activity maximum is at relatively low temperature, but catalyst activity decreases drastically if polymerization is desired at higher temperature
Solution Approach 1:
The invention uses composite materials by combining specific Mg compounds (such as Mg(OH)2, MgO, or Mg(OH)Cl) with transition metal compounds (Ti, V, Zr, or Hf halides or alkoxides) in defined ratios and configurations. This composite structure, formed through controlled precipitation, creates catalyst particles with enhanced thermal stability and shifted activity maximum to higher temperatures while maintaining high activity
Solution Approach 2:
The invention applies parameter changes to the catalyst composition, specifically adjusting the Mg to transition metal ratio, the type of Mg compound used, and the presence of electron donors or donors, to shift the catalyst activity temperature profile. These compositional parameter changes result in catalysts that maintain high activity at polymerization temperatures above 70°C
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 catalysts with excellent morphology, uniform particle size distribution, and maintained activity at higher temperatures, suitable for polymerization processes above 70°C, with improved catalyst performance and polymer properties.
Implementation Method 1
preparing a solution of a complex of a Group 2 metal and an electron donor by reacting a compound of said metal with said electron donor or a precursor thereof in an organic liquid reaction medium
Implementation Method 2
adding said solution of said complex to at least one compound of a transition metal to produce an emulsion the dispersed phase of which contains more than 50 mol % of the Group 2 metal in said complex
Implementation Method 3
agitating the emulsion in order to maintain the droplets of said dispersed phase within an average size range of 5 to 200 μm
Implementation Method 4
solidifying said droplets of the dispersed phase
Implementation Method 5
recovering the solidified particles of the olefin polymerisation catalyst component
Data Source
AI summary
The invention refers to a process for preparing a Group 2 metal/transition metal olefin polymerization catalyst component in particulate form having an improved high temperature activity and the use thereof in a process for polymerizing olefins.