Di-phosphine Ligand Chromium Catalyst for Ethylene Trimerization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current olefin oligomerization catalysts for ethylene trimerization, such as those using chromium complexes, face challenges in productivity and selectivity for producing desired oligomers like 1-hexene and 1-octene, with existing ligands often resulting in low activity or no product formation.
Innovation Solution
The use of specific di-phosphine ligands characterized by a general formula with phosphorus atoms connected by a bridging group, in combination with a chromium precursor and activators, to form a catalytic composition that selectively oligomerizes ethylene, focusing on achieving high selectivity for 1-hexene and 1-octene production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional chromium catalysts with existing ligands are used for ethylene oligomerization, then the catalytic system can operate, but the productivity and selectivity for desired oligomers (1-hexene and 1-octene) are low
Solution Approach 1:
The patent changes the chemical parameters of the ligand system by introducing specific di-phosphine ligands with controlled steric and electronic properties. The ligands feature phosphorus atoms connected by bridging groups (such as -CH2-, -CH(CH3)-, -C(CH3)2-, cyclohexyl, or phenyl groups) with specific R-group substitutions (combinations of H, alkyl, aryl, and heteroaryl groups). These parameter changes in ligand structure directly improve both the activity (productivity) and selectivity for C6 and C8 oligomers while minimizing polymer formation.
2Reliability
If existing ligands are used with chromium precursors, then the catalyst can be formed, but the activity is low or no product formation occurs
Solution Approach 1:
The patent systematically varies key parameters of the ligand structure including the bridging group type (methylene, ethylene, cyclohexyl, phenyl), the R-substituents (H, alkyl, aryl, heteroaryl combinations), and the overall ligand geometry. These parameter changes optimize the electronic and steric environment around the chromium center, ensuring reliable catalyst formation with high activity and consistent product formation across different chromium precursors and 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 selective oligomerization of ethylene with high selectivity, producing desired oligomers with at least 70% yield and minimizing polymer formation, thereby improving the efficiency and productivity of the ethylene trimerization process.
Implementation Method 1
The use of specific di-phosphine ligands characterized by a general formula with phosphorus atoms connected by a bridging group, in combination with a chromium precursor and activators, to form a catalytic composition that selectively oligomerizes ethylene
Implementation Method 2
This approach enables selective oligomerization of ethylene with high selectivity, producing desired oligomers with at least 70% yield and minimizing polymer formation
Data Source
AI summary
This invention relates to a method to selectively oligomerize olefins comprising contacting olefins with: 1) at least one diaryl-substituted diphosphine ligand; 2) a chromium metal precursor; and 3) optionally, one or more activators. In a particular embodiment, the method for selectively oligomerizing olefins includes trimerizing ethylene to selectively form 1-hexene.