Halogen-Substituted Phosphine Ligand for Ethylene Trimerization
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Solution Overview
Problem
Current ethylene oligomerization catalysts face challenges in achieving high activity and selectivity, particularly in ethylene trimerization and tetramerization reactions, with excessive by-product generation, such as cycloolefins and cyclized products, which negatively impacts process economics.
Innovation Solution
A halogen-containing compound is used as a ligand in an ethylene oligomerization catalyst composition, comprising a specific formula with fluorine or chlorine substituents, combined with a transition metal compound and co-catalyst, to enhance catalytic performance, achieving high activity and selectivity in ethylene trimerization and tetramerization reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional catalysts are used for ethylene oligomerization, then the reaction can proceed, but the catalytic activity is insufficient and by-product generation is excessive
Solution Approach 1:
The patent modifies the ligand structure by introducing halogen atoms (fluorine or chlorine) at specific positions (R1-R4) on the phosphine backbone, changing the chemical parameters of the catalyst system to achieve superior activity and selectivity
Solution Approach 2:
The patent creates a composite catalyst system combining transition metal compounds (chromium, molybdenum, iron, titanium, zirconium) with specially designed halogen-containing phosphine ligands and co-catalysts, achieving synergistic effects that improve both activity and reduce by-products
2Productivity
If existing catalyst systems are used, then ethylene oligomerization can be achieved, but the selectivity for desired products (1-hexene and 1-octene) is insufficient
Solution Approach 1:
The patent introduces halogen atoms at specific local positions (R1-R4) on the phosphine ligand backbone, creating localized electronic effects that enhance the catalyst's ability to differentiate between reaction pathways and improve selectivity for 1-hexene and 1-octene
Solution Approach 2:
The patent systematically varies the halogen substitution pattern (different R1-R4 combinations) to optimize the electronic and steric properties of the ligand, thereby fine-tuning the catalyst's selectivity for desired oligomerization products
3Speed
If conventional catalysts are used, then the reaction can proceed, but the initiation speed is slow and long-term stability is poor
Solution Approach 1:
The patent modifies the ligand's electronic parameters by introducing halogen atoms, which enhance the metal center's electrophilicity and accelerate ethylene coordination and insertion, resulting in faster initiation and sustained activity
Solution Approach 2:
The patent combines the halogen-containing phosphine ligand with specific transition metal compounds and co-catalysts to create a composite system where the ligand's electronic effects synergistically enhance both initiation speed and long-term catalytic stability
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 composition exhibits significantly improved catalytic activity and selectivity, with maximum activity exceeding 4×10^8 g/mol(Cr)·h and total selectivity of 1-hexene and 1-octene exceeding 92wt%, along with rapid initiation and long-term stability, reducing by-product formation.
Implementation Method 1
ethylene oligomerization catalyst composition, including at least one halogen-containing compound selected from the first aspect of the present invention, at least one transition metal compound and at least one co-catalyst
Data Source
AI summary
Disclosed are a halogen-containing compound as shown in a formula I and use thereof as a ligand for an ethylene oligomerization catalyst composition; and further disclosed are an ethylene oligomerization catalyst composition containing the halogen-containing compound, and ethylene oligomerization, trimerization and tetramerization methods using the catalyst composition. As a ligand of a catalyst for ethylene oligomerization, a fluoropolymer can effectively improve the catalytic performance of a catalyst system, and particularly exhibits significantly improved activity and selectivity in an ethylene oligomerization reaction. The catalyst composition has better industrial application prospects and economic value.