Homogeneous Catalyst Preparation for 1-Hexene Production
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Solution Overview
Problem
Existing catalyst compositions for the selective production of linear alpha olefins, such as 1-hexene, have a short shelf life, requiring precise metering and handling, and are prone to degradation, limiting their operational window and efficiency in ethylene oligomerization processes.
Innovation Solution
A two-step method for preparing a homogenous catalyst involving the preparation and storage of pre-catalyst solutions comprising a modifier and an organoaluminum compound, and a chromium-containing compound, with recirculation and temperature control to extend the catalyst's shelf life and maintain activity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the homogenous catalyst is prepared with all four components (chromium compound, ligand, modifier, and activator) in a single mixture, then high productivity and high selectivity for 1-hexene can be achieved, but the catalyst degrades rapidly with a shelf life of approximately one day or less
Solution Approach 1:
The catalyst system is divided into separate components: a first pre-catalyst solution containing the chromium compound and ligand, and a second pre-catalyst solution containing the modifier and activator. These components are prepared and stored separately to prevent degradation, then combined immediately before use in the oligomerization reactor. This segmentation allows each component to be stabilized independently while maintaining the ability to form the active catalyst system when needed.
Solution Approach 2:
The pre-catalyst solutions are prepared in advance and stored in stable forms for extended periods. The first pre-catalyst solution is prepared by reacting chromium compound with ligand in aromatic solvent, and the second pre-catalyst solution is prepared by reacting modifier with activator. These preliminary preparations allow the components to be stored stably and then combined just before use, ensuring high activity while extending shelf life.
2Manufacturing precision
If the catalyst components are meticulously metered into the reactor using dosing pumps to achieve precise molar ratios, then high selectivity and productivity are achieved, but the system cannot use slurry systems or solid handling methods and requires complex dosing infrastructure
Solution Approach 1:
Multiple catalyst components are pre-combined into two consolidated pre-catalyst solutions: the first solution combines chromium compound and ligand, while the second combines modifier and activator. These merged solutions are then introduced into the reactor in a simplified manner, reducing the need for multiple individual dosing pumps and complex metering infrastructure while maintaining precise compositional control.
Solution Approach 2:
The catalyst system is transformed from requiring precise metering of four separate solid or liquid components into using two pre-mixed liquid solutions with defined compositions. This parameter change in the physical state and pre-formulation of catalyst components simplifies the dosing system requirements while maintaining the ability to achieve the necessary molar ratios for high selectivity.
3Reliability
If the catalyst components are stored in separate vessels and then mixed before use, then the catalyst activity is maintained, but ingress of moisture or air from the environment must be prevented during unloading and handling
Solution Approach 1:
The pre-catalyst solutions are prepared and handled in an inert atmosphere environment, typically using nitrogen or argon gas to displace air and prevent moisture ingress. The solutions are stored in sealed vessels under inert gas pressure, and transfer operations are conducted through inerted piping systems. This creates a protective atmosphere that prevents harmful reactions with moisture and oxygen throughout the catalyst handling process.
Solution Approach 2:
The aromatic solvent (such as toluene or xylene) serves as an intermediary medium that dissolves the catalyst components and provides a stable, moisture-excluding environment. The solvent acts as a barrier against moisture ingress and facilitates the handling and transfer of catalyst components without direct exposure to atmospheric conditions, thereby protecting the sensitive catalyst from degradation.
4Reliability
If the catalyst is prepared directly before injection into the reactor with minimum transportation time, then catalyst activity is assured, but the preparation must be done immediately and cannot be stored for extended periods
Solution Approach 1:
The catalyst preparation is segmented into two stable pre-catalyst solutions that can be prepared in advance and stored separately. The first pre-catalyst solution contains the chromium compound and ligand, while the second contains the modifier and activator. These segmented components can be stored for extended periods without degradation, and are only combined immediately before injection into the reactor, thus maintaining high activity while allowing advance preparation.
Solution Approach 2:
The pre-catalyst solutions are prepared in advance as preliminary steps before the actual oligomerization reaction. These preliminary preparations involve reacting chromium compound with ligand in aromatic solvent, and separately reacting modifier with activator. The resulting stable pre-catalyst solutions can be stored and then combined just before use, ensuring maximum catalyst activity while allowing time-efficient preparation procedures.
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 method extends the catalyst's shelf life, allowing for more stable and efficient production of linear alpha olefins by maintaining catalyst activity over a longer period, reducing the risk of thermal runaways and side product formation, and enabling more precise control over the oligomerization process.
Implementation Method 1
prior to adding the first pre-catalyst solution to the catalyst pre-formation unit, the first pre-catalyst solution in the first vessel is recirculated through a first pump and a first cooler, and continuously returned to the first vessel
Implementation Method 2
wherein the first pre-catalyst solution is maintained at a temperature of 0-50°C, preferably, 10-40°C, more preferably 15-35°C
Implementation Method 3
forming a homogenous catalyst by mixing the first pre-catalyst solution and the second pre-catalyst solution; adding the homogeneous catalyst to a reaction vessel, wherein the reaction vessel comprises an alpha olefin; and forming the linear alpha olefin by mixing the homogeneous catalyst and the alpha olefin
Data Source
Figure 1~2
AI summary
A method for preparing a homogenous catalyst for the production of linear alpha olefins includes: preparing a first pre-catalyst solution comprising a modifier and an organoaluminum compound in a first solvent wherein the first pre-catalyst solution is reacted and stored in a first vessel for a period of time of 1 hour to 90 days; preparing a second pre- catalyst solution comprising a second solvent, a ligand, and a chromium containing compound, wherein the second pre-catalyst solution is stored in a second vessel for a period of time of 1 hour to 90 days; and after a period of time, adding the first pre-catalyst solution to a catalyst pre-formation unit; after the same period of time, adding the second pre-catalyst solution to the catalyst pre-formation unit; forming a homogenous catalyst by mixing the first pre-catalyst solution and the second pre-catalyst solution; adding the homogeneous catalyst to a reaction vessel, wherein the reaction vessel comprises an alpha olefin; and forming the linear alpha olefin by mixing the homogeneous catalyst and the homogenous catalyst.