Ziegler-Natta Catalyst Washing Process for Polymerization Stability
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Solution Overview
Problem
Current Ziegler-Natta catalyst preparation methods often result in undesired polymerization disturbances, such as plugging and reduced flowability, and fail to produce polypropylenes with finely tuned mechanical properties like increased crystallinity and melting temperature, while also experiencing activity reduction in sequential polymerization processes.
Innovation Solution
A modified washing process for Ziegler-Natta catalyst preparation involving specific steps with aromatic and aliphatic hydrocarbons and titanium tetrachloride, including temperature control between 80°C to 120°C, to enhance catalyst properties and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional washing steps are used in Ziegler-Natta catalyst preparation, then the catalyst can be produced, but undesired polymerization disturbances occur such as plugging and reduced flowability
Solution Approach 1:
The patent applies parameter changes by modifying the washing process parameters: using a two-stage washing method where the first stage uses a non-aromatic solvent at ambient temperature and the second stage uses an aromatic solvent at elevated temperature (80-120°C). This systematic parameter modification eliminates polymerization disturbances while maintaining catalyst performance stability.
2Manufacturing precision
If conventional washing methods are used, then the preparation process is simple, but the polypropylene lacks finely tuned mechanical properties like increased crystallinity and melting temperature
Solution Approach 1:
The washing process is segmented into two distinct stages: first washing with a non-aromatic solvent to remove specific impurities, then washing with an aromatic solvent at elevated temperature to achieve desired crystallinity and melting temperature. This segmentation enables precise control of mechanical properties while maintaining reasonable process complexity.
3Productivity
If standard washing procedures are applied, then the catalyst preparation is straightforward, but activity reduction occurs in sequential polymerization processes
Solution Approach 1:
The patent utilizes parameter changes by implementing a two-stage washing protocol with different solvents and temperatures. The first stage removes catalyst poisons that would cause activity reduction, while the second stage optimizes catalyst surface properties. This maintains high catalyst activity in sequential polymerization processes despite increased washing process complexity.
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 modified washing process improves catalyst properties, leading to polypropylenes with increased crystallinity and melting temperature, reduced XCS content, and minimized activity decay, facilitating broader application in existing catalyst preparation processes.
Implementation Method 1
washing said solid catalyst component particles with a wash solution of titanium tetrachloride and internal electron donor (ID)
Implementation Method 2
washing said solid catalyst component particles with a wash solution of titanium tetrachloride and internal electron donor (ID)
Implementation Method 3
wherein at least one of the one or more washes with a wash solution of titanium tetrachloride and internal electron donor (ID) of step d2) is conducted at a temperature in the range from 80 to 120° C.
Data Source
AI summary
A process for forming a Ziegler-Natta catalyst component, wherein a certain combination of washing steps is employed, enabling the provision of inventive catalysts capable of synthesising polypropylenes with increased melting temperature, decreased XCS content, as well as more efficiently maintaining catalyst activity across sequential polymerization processes.