Halogen-Substituted Catalyst for Selective Ethylene Oligomerization
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Solution Overview
Problem
Conventional ethylene oligomerization reactions produce significant amounts of butene, high-grade oligomers, and polyethylene alongside 1-hexene and 1-octene, limiting desired product yield, and existing catalysts face issues with solubility in aliphatic hydrocarbon solvents, making it difficult to control catalyst amount and maintain reaction activity over time.
Innovation Solution
A catalyst system comprising a transition metal or its precursor, a halogen-substituted organic ligand, and a heteroatom ligand, specifically designed to enhance solubility in aliphatic hydrocarbons, improving reaction activity and selectivity for 1-hexene and 1-octene production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional oligomerization reaction is used, then various α-olefins are produced according to Schulze-Flory or Poisson product distribution, but desired product yield is limited due to significant production of butene, high-grade oligomer, and polyethylene
Solution Approach 1:
The patent modifies the chemical parameters of the catalyst system by incorporating specific heteroatom ligands (nitrogen, oxygen, sulfur-containing ligands) with defined coordination modes and steric environments. This changes the electronic and steric parameters at the metal center, enabling selective oligomerization to 1-hexene or 1-octene while suppressing formation of other by-products according to the Schulze-Flory or Poisson distributions
Solution Approach 2:
The patent creates a composite catalyst system combining transition metal centers (chromium, molybdenum, tungsten, titanium, tantalum, vanadium, or zirconium) with specially designed heteroatom ligands and halogen-substituted organic ligands. This composite structure enables simultaneous achievement of high activity and selectivity for specific oligomers while minimizing by-product formation
2Ease of operation
If existing catalysts are used, then oligomerization reaction can proceed, but solubility in aliphatic hydrocarbon solvents is poor, making it difficult to control catalyst amount
Solution Approach 1:
The patent modifies the physical parameters of the catalyst by introducing halogen-substituted organic ligands with specific hydrophobic characteristics. This changes the solubility parameters of the catalyst complex, enabling it to dissolve readily in aliphatic hydrocarbon solvents while maintaining catalytic activity and allowing precise control of catalyst amount
3Productivity
If PNP skeletal ligand is used, then tetramerization or trimerization can occur, but reaction activity is not consistently maintained and reaction rate is greatly reduced according to reaction time
Solution Approach 1:
The patent creates a more stable composite ligand structure by combining heteroatom ligands with halogen-substituted organic ligands. This composite ligand system provides both strong coordination to the metal center (maintaining activity over time) and appropriate steric environment (maintaining selectivity), resolving the instability issue of PNP skeletal ligands
Solution Approach 2:
The halogen-substituted organic ligand acts as an intermediary that stabilizes the metal-ligand interaction. It mediates between the heteroatom ligand and the metal center, providing additional coordination stability and preventing ligand dissociation that would otherwise occur with PNP skeletal ligands alone
4Productivity
If aromatic compound is used as polymerization solvent, then catalyst solubility is improved, but activity is lower compared to aliphatic hydrocarbon compound
Solution Approach 1:
The patent changes the solvent parameter from aromatic to aliphatic hydrocarbon by modifying the catalyst's solubility characteristics through halogen-substituted organic ligands. This enables the use of aliphatic solvents which provide higher reaction activity while the catalyst remains sufficiently soluble for practical operation
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 catalyst system achieves high activity and selectivity for 1-hexene and 1-octene production, with improved solubility in aliphatic hydrocarbons allowing easier catalyst control and reduced residual solvent issues, enhancing operational stability and reducing environmental and human toxicity concerns.
Implementation Method 1
an oligomerization catalyst including a transition metal or transition metal precursor, a halogen-substituted organic ligand, and a heteroatom ligand
Implementation Method 2
a highly active and highly selective ethylene oligomerization catalyst for being used in an oligomerization reaction such as trimerization or tetramerization of ethylene
Data Source
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AI summary
The present invention relates to an oligomerization catalyst comprising a transition metal or transition metal precursor, a halogen-substituted organic ligand, and a heteroatom ligand, and to a method for selectively preparing 1-hexene or 1-octene from ethylene using the catalyst.