Chromium Catalyst Selective Ethylene Oligomerization
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Solution Overview
Problem
There is a challenge in developing alpha olefin oligomerization techniques that do not use triethylaluminum (TEA) as part of the catalyst system, particularly in achieving efficient and economic production of linear alpha olefins, as alternative techniques often require extensive secondary processing to recover desired products from undesired fractions like butene or waxes.
Innovation Solution
The use of a chromium-based catalyst system comprising N2-phosphinyl amidine, formamidine, or guanidine chromium compound complexes in combination with aluminoxane, in the presence of an organic reaction medium and optionally hydrogen, to selectively oligomerize ethylene and produce linear alpha olefins without forming ethylene oligomers in situ.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If alternative catalyst systems are used to avoid TEA, then the drawbacks of homogeneous catalyst systems are avoided, but polymer formation occurs during startup and operation
Solution Approach 1:
The patent introduces a C3+ olefin before introducing ethylene to the reaction zone. This preliminary action of having C3+ olefin already present in the reaction zone prevents polymer formation during startup by ensuring that when ethylene is subsequently introduced, the catalyst system is already engaged in productive oligomerization rather than forming unwanted polymers.
Solution Approach 2:
The C3+ olefin acts as an intermediary substance that mediates between the catalyst system and ethylene. By being present in the reaction zone first, it facilitates the catalyst's selective oligomerization of ethylene while preventing harmful polymer formation, thus serving as a protective intermediary in the catalytic process.
2Object-generated harmful factors
If C3+ olefin is introduced before ethylene, then polymer formation is reduced, but process complexity increases
Solution Approach 1:
The patent maintains continuous presence of C3+ olefin in the reaction zone throughout the oligomerization process. This continuous action ensures that the catalyst system remains engaged in productive oligomerization pathways, preventing polymer formation during both startup and normal operation without requiring additional processing steps.
3Object-generated harmful factors
If ethylene is diluted with organic reaction medium, then polymer formation is reduced, but productivity decreases
Solution Approach 1:
The patent changes the compositional parameter of the reaction zone by introducing C3+ olefin, which alters the reaction kinetics and catalyst behavior. This parameter change enables selective oligomerization of ethylene while suppressing polymer formation, achieving both reduced harmful factors and maintained productivity through optimized reaction conditions.
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 approach enables the selective production of ethylene oligomers with reduced polymer formation during startup and normal operation, improving productivity and preventing fouling of reaction zone components, thus enhancing the efficiency and stability of the oligomerization process.
Implementation Method 1
a catalyst system comprising (a) a chromium component comprising an N2-phosphinyl amidine, formamidine, or guanidine chromium compound complex
Implementation Method 2
a catalyst system comprising (a) a chromium component comprising an N2-phosphinyl amidine, formamidine, or guanidine chromium compound complex in combination with aluminoxane
Data Source
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AI summary
Disclosed are processes, systems, and reaction systems for the oligomerization of ethylene to form an ethylene oligomer product in a reaction zone using a catalyst system comprising (a) a chromium component comprising an N2-phosphinyl amidine chromium compound complex, an N2-phosphinyl formamidine chromium compound complex, an N2-phosphinyl guanidine chromium compound complex, or any combination thereof, and (b) an aluminoxane. A C3+ olefin can be present in the reaction zone for a period of time, where the C3+ olefin is not an ethylene oligomer formed in-situ within the reaction zone.