NPNPN Ligand Chromium Catalyst for 1-Hexene Selectivity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing catalyst systems for the oligomerization of ethylene suffer from low selectivity and purity for 1-hexene, leading to the production of unwanted byproducts such as C10+ hydrocarbons and polymer formation, which increases costs and complicates market adaptation due to varying market demands for different ethylene-derived oligomers.
Innovation Solution
A catalyst composition featuring a chromium (III) species and a NPNPN ligand system with specific terminal amine alkyl substituents and phosphorous substituents, such as cyclohexyl groups, is used to achieve high selectivity and purity for 1-hexene production, minimizing solvent insoluble materials and optimizing reaction conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If existing catalyst systems are used for ethylene oligomerization, then the production of 1-hexene is achieved, but the selectivity for 1-hexene is low and unwanted byproducts such as C10+ hydrocarbons and polymer are formed
Solution Approach 1:
The patent modifies the catalyst system by changing the ligand structure parameters - specifically using NPNPN ligands with particular alkyl substituents on nitrogen atoms and cyclohexyl groups on phosphorus atoms. This chemical parameter change enables the catalyst to achieve >80 wt.% selectivity for 1-hexene while suppressing formation of unwanted byproducts like C10+ hydrocarbons and polymer, directly resolving the contradiction between manufacturing precision and harmful byproduct generation.
2Productivity
If existing catalyst systems are used, then ethylene oligomerization proceeds, but polymer formation occurs leading to equipment fouling and yield loss
Solution Approach 1:
The catalyst system parameters are changed by introducing specific NPNPN ligands with cyclohexyl groups on phosphorus atoms and particular alkyl substituents on nitrogen atoms. This parameter modification shifts the reaction pathway to favor 1-hexene production while suppressing polymerization reactions, thereby maintaining productivity and eliminating harmful polymer formation that causes equipment fouling and yield loss.
3Manufacturing precision
If existing catalyst systems are used, then the oligomerization reaction occurs, but the production costs increase due to low selectivity and need for additional purification
Solution Approach 1:
The patent changes the catalyst composition parameters by using NPNPN ligands with specific substituent patterns. This parameter change achieves >80 wt.% selectivity for 1-hexene with minimal unwanted byproducts, thereby reducing the need for additional purification steps and lowering production costs while maintaining high product purity, thus resolving the contradiction between manufacturing precision and ease of manufacture.
4Productivity
If existing catalyst systems are used, then ethylene conversion occurs, but the catalyst activity is poor resulting in increased cost per kg product
Solution Approach 1:
The catalyst system parameters are modified by introducing NPNPN ligands with specific structural features (cyclohexyl groups on phosphorus, alkyl substituents on nitrogen). This parameter change significantly improves catalyst activity and turnover rate, thereby increasing productivity and reducing the cost per kg of 1-hexene product, resolving the contradiction between productivity and manufacturing cost.
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 achieves greater than 80 wt.% selectivity for 1-hexene with less than 3 wt.% solvent insoluble material, enhancing product purity and reducing production costs by suppressing polymer formation and adapting to market demands effectively.
Implementation Method 1
A catalyst composition for the oligomerization of ethylene to 1-hexene. The catalyst composition contains a chromium (III) species and a ligand having the formula of: [ligand structure]
Data Source
AI summary
Catalyst compositions and processes for the oligomerization of ethylene to 1-hexene are described. The catalyst composition includes a triamino bisphospino (NPNPN) ligand system with specific phosphorous and nitrogen ligands. The terminal nitrogen atoms include linear alkyl hydrocarbons that differ in the number of carbon atoms by 3.