Supported Constrained Geometry Catalyst Polymerization
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Solution Overview
Problem
Gas phase polyolefin production reactors face disruptions due to the formation of solid polymer masses on reactor walls, known as sheeting or chunking, which interfere with fluidization and product discharge, leading to reactor shut-downs and decreased catalyst efficiencies when using metallocene catalysts.
Innovation Solution
A polymerization process utilizing a metallocene-based catalyst system comprising a supported constrained geometry catalyst, at least one monomer, and an additive such as aluminum distearate or ethoxylated amine in a gas-phase reactor system to prevent sheeting and ensure continuous operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If metallocene catalysts are used in gas phase reactors, then catalyst productivity is improved, but sheeting and chunking occur leading to reactor discontinuity
Solution Approach 1:
The patent introduces static control agents as intermediary substances that mediate between the metallocene catalyst system and the reactor walls. These agents (such as polyethylene glycol, polypropylene glycol, or their esters) are added in small amounts (0.1-100 ppm) to control static electricity buildup on the reactor walls, preventing polymer sheets from adhering while maintaining catalyst productivity.
Solution Approach 2:
The patent changes the electrical parameter (static charge) on the reactor walls by introducing static control agents. This parameter change prevents the adhesion of polymer sheets to the walls by modifying the electrostatic interactions between the polymer and reactor surface, thereby eliminating sheeting and chunking problems while maintaining continuous operation.
2Object-affected harmful factors
If static control agents are added to control static charges, then sheeting is reduced, but catalyst efficiency decreases
Solution Approach 1:
The patent applies partial action by using very small amounts of static control agents (0.1-100 ppm) rather than large quantities. This minimal dosing is sufficient to control static charges and prevent sheeting while avoiding the negative effects of excessive additive concentrations that would inhibit catalyst activity and reduce polymerization efficiency.
Solution Approach 2:
The patent precisely controls the concentration parameter of static control agents to optimize the balance between static control and catalyst efficiency. By maintaining agents within the 0.1-100 ppm range, the electrostatic properties are modified enough to prevent sheeting while keeping catalyst activity unaffected.
3Quantity of substance
If reactor walls accumulate static charge, then polymer sheets form on walls, but disrupting fluidization and product discharge
Solution Approach 1:
Static control agents act as intermediary substances between the polymer and reactor walls, preventing direct adhesion. These agents (polyethylene glycol, polypropylene glycol, or their esters) reduce the electrostatic attraction between polymer sheets and walls, allowing polymer to accumulate in the fluidized bed without forming adherent sheets on reactor surfaces, thereby maintaining proper fluidization and discharge.
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 achieves reliable and cost-effective continuous polyolefin production by reducing static electricity and minimizing sheeting, thereby maintaining reactor continuity and catalyst productivity.
Implementation Method 1
The process achieves reliable and cost-effective continuous polyolefin production by reducing static electricity and minimizing sheeting
Implementation Method 2
contacting a metallocene-based catalyst system comprising a supported constrained geometry catalyst, at least one monomer, and an additive in a gas-phase reactor system under polymerization conditions for creating a polymer product
Data Source
AI summary
A polymerization process includes contacting the following in a gas-phase reactor system under polymerization conditions for making a polymer product: a metallocene-based catalyst system including a supported constrained geometry catalyst, at least one monomer, and an additive selected from a group consisting of an aluminum distearate, an ethoxylated amine, and a mixture thereof. The additive may be selected from a group consisting of an aluminum distearate, an ethoxylated amine, polyethylenimines, and other additives suitable for use in the production of polymers for food contact applications and end products, including a mixture of a polysulfone copolymer, a polymeric polyamine, and oil-soluble sulfonic acid, in a carrier fluid, and mixtures thereof.