Chromium Catalyst Ethylene Oligomerization Selectivity
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Solution Overview
Problem
Existing ethylene oligomerization methods produce significant amounts of polyethylene, which impede process stability and require high amounts of expensive methylaluminoxane, while also suffering from decreased catalytic activity at high temperatures.
Innovation Solution
The method involves reacting a chromium complex represented by a specific chemical formula with an organoaluminium compound and ethylene in the presence of an organic solvent at less than 60°C, significantly reducing polyethylene production and maintaining high catalytic activity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a chromium trivalent compound, bisphosphine ligand, and methylaluminoxane (MAO) are used as a catalyst system for ethylene oligomerization, then 1-octene and 1-hexene can be produced with high selectivity, but a large amount of polyethylene is produced which seriously impedes process stability
Solution Approach 1:
The patent changes the chemical parameters of the catalyst system by replacing methylaluminoxane (MAO) with alternative co-catalysts such as aluminoxane modified with specific compounds or other organometallic compounds. This parameter change maintains the oligomerization activity while significantly reducing polyethylene production, thereby improving process stability without sacrificing selectivity for 1-octene and 1-hexene
Solution Approach 2:
The patent employs co-catalysts with controlled lifetimes and activities that prevent excessive polyethylene formation. By using co-catalysts that are consumed or deactivated at appropriate rates, the system maintains high selectivity for desired oligomers while avoiding the accumulation of polyethylene by-products that would compromise process stability
2Productivity
If the temperature is increased to maintain catalytic activity, then production efficiency improves, but the catalytic activity of the oligomerization catalyst system decreases and by-product production increases causing tube clogging and fouling
Solution Approach 1:
The patent optimizes the temperature parameter within a specific range (20-80°C) and changes the chemical composition parameters by introducing alternative co-catalysts and modifying the catalyst structure. These parameter changes enable the system to maintain high catalytic activity at moderate temperatures while suppressing polyethylene by-product formation, thereby avoiding tube clogging and fouling without compromising productivity
Solution Approach 2:
The patent introduces specific co-catalysts and additives that act as intermediaries to mediate between the catalyst and ethylene substrate. These intermediaries facilitate the oligomerization reaction at lower temperatures while preventing the formation of excessive polyethylene, thus resolving the conflict between productivity and harmful by-product generation
3Productivity
If a large amount of methylaluminoxane (MAO) is used to achieve commercially usable activity level, then catalyst activity is sufficient, but the cost increases significantly
Solution Approach 1:
The patent replaces expensive methylaluminoxane (MAO) with more economical co-catalysts such as aluminoxane modified with specific compounds or other organometallic compounds. These alternative co-catalysts achieve comparable or sufficient catalytic activity at lower costs and in smaller quantities, thereby reducing the quantity of substance required while maintaining productivity
Solution Approach 2:
The patent changes the chemical composition parameters of the co-catalyst system to use less expensive materials with appropriate activity levels. By optimizing the ratio and type of co-catalyst, the system achieves commercially usable activity without requiring large amounts of expensive MAO, thus reducing both cost and quantity of substances involved
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 produces 1-hexene and 1-octene with high selectivity while dramatically reducing polyethylene production, enhancing process stability, and maintaining catalyst activity, even at low temperatures.
Implementation Method 1
reacting a chromium complex represented by chemical formula 1 and an organoaluminium compound represented by chemical formula 2 with ethylene
Implementation Method 2
ethylene oligomerization reaction
Data Source
AI summary
The present invention provides: an ethylene oligomerization method in which an ethylene oligomer is produced by reacting a chromium complex and an organic aluminium compound with ethylene; and the ethylene oligomer thereof.