Comonomer Synthesis Reactor Process Simplification
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Solution Overview
Problem
Current processes for generating linear alpha olefin comonomers like 1-butene, 1-hexene, and 1-octene from ethylene are costly and complex, involving separate production plants and extensive separation and handling procedures.
Innovation Solution
A simplified process using comonomer synthesis reactors and downstream gas/liquid phase separators to produce and separate 1-butene, 1-hexene, and 1-octene from ethylene, eliminating the need for cryogenic distillation and reducing capital and operational costs by recycling unconverted ethylene and discharging deactivated catalyst with the comonomer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If separate plants are used to produce comonomers from ethylene, then comonomer production is achieved, but capital cost and operational complexity increase significantly
Solution Approach 1:
The patent combines comonomer production directly within the polyethylene polymerization plant by integrating a comonomer synthesis reactor that converts ethylene to linear alpha olefins (1-butene, 1-hexene, 1-octene) on-site. This eliminates the need for separate comonomer production plants and reduces capital investment in dedicated comonomer facilities, while also simplifying transport, storage, and handling operations.
Solution Approach 2:
The patent employs a multi-functional approach where the same ethylene feedstock serves dual purposes: it is used both for polyethylene polymerization and for in-situ comonomer synthesis. The comonomer synthesis reactor uses ethylene to produce linear alpha olefins that are then used as comonomers in the polymerization process, creating a self-sufficient system that reduces external material purchases and simplifies the overall process architecture.
2Manufacturing precision
If extensive separation and handling procedures are used, then comonomer purity is achieved, but operational costs and process complexity increase
Solution Approach 1:
The patent extracts only the necessary comonomer fraction from the reaction mixture by using a comonomer synthesis reactor that selectively produces linear alpha olefins (C4-C8) from ethylene. The reactor design and catalyst selection enable selective trimerization and tetramerization, producing the desired comonomers with high selectivity (90-95%) while minimizing byproducts, thereby reducing the need for extensive separation and purification equipment.
3Productivity
If cryogenic distillation columns are used for ethylene separation, then unconverted ethylene is recovered, but capital cost and energy consumption increase
Solution Approach 1:
The patent changes the operating parameters of the separation system by using gas-liquid phase separators operated at elevated pressures (e.g., 300-500 psig) and temperatures (e.g., 20-50°C) instead of cryogenic conditions. This allows unconverted ethylene to be recovered as a gas phase while the comonomer product remains in the liquid phase, eliminating the need for energy-intensive cryogenic distillation columns and significantly reducing both capital cost and energy consumption.
4Reliability
If elaborate catalyst recovery and separation systems are used, then catalyst is recovered, but device complexity and operational costs increase
Solution Approach 1:
The patent adopts a pragmatic approach where the catalyst is allowed to become deactivated and is discarded along with the comonomer product stream. The comonomer synthesis reactor uses homogeneous catalysts that become deactivated after a period of operation, and instead of implementing complex catalyst recovery and separation systems, the entire liquid effluent containing both comonomer and deactivated catalyst is sent to storage or further processing, significantly simplifying the overall process architecture.
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 process achieves substantial capital and operational cost savings, simplifies the production process, and allows for high selectivity and activity through catalyst selection, eliminating the need for elaborate catalyst recovery and separation systems.
Implementation Method 1
passing the effluent stream to the one or more downstream gas/liquid phase separators to form a gas stream of the unreacted ethylene monomer, and a liquid stream of the comonomer and the catalyst in a solvent
Data Source
AI summary
The present invention relates to a method for preparing linear alpha olefin comonomers, such as 1-butene, 1-hexene or 1-octene, from ethylene monomer. The comonomer generated is stored on site for use in a subsequent process, such as a polyethylene polymerization reactor. The method includes the steps of feeding an ethylene monomer, and a catalyst in a solvent to one or more comonomer synthesis reactors; reacting the ethylene monomer and the catalyst in solvent under reaction conditions to produce an effluent stream comprising unreacted ethylene monomer, a catalyst in a solvent, and comonomer; passing the effluent stream to one or more downstream gas/liquid phase separators to form a gas stream of unreacted ethylene monomer, and a liquid stream of comonomer, and catalyst in a solvent; recycling to the one or more comonomer synthesis reactors the unreacted ethylene monomer and a portion of the liquid stream; and storing a remaining portion of said liquid stream for subsequent processing of the comonomer. Some of the benefits of the method include process simplification and reduced capital and operating costs from, inter alia, not having to recover ethylene in high purity nor separate catalyst from comonomer.