Zirconium Amide Catalyst for Ethylene Oligomerization
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Solution Overview
Problem
Existing catalyst systems for ethylene oligomerization face challenges such as poor solubility, high production of wax and high molecular weight polyethylene, low selectivity, and polymer formation, which affect the purity and distribution of linear alpha-olefins.
Innovation Solution
A catalyst composition comprising a zirconium amide compound, an organoaluminum compound, and an additive, specifically tetrachlorobis(N,N-diisobutylacetamide)zirconium and trialkylaluminum, is used for ethylene oligomerization, with the zirconium amide compound prepared by reacting a zirconium component with a substituted amide in the presence of an organic solvent, to achieve high activity and broad weight percent distribution of linear oligomers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If zirconium halide or zirconium tetrachloride is used as catalyst, then catalytic activity is achieved, but solubility in hydrocarbon solvent is poor and wax/high molecular weight polyethylene is produced in large amount
Solution Approach 1:
The patent changes the chemical parameters of the zirconium catalyst by replacing halide ligands with amide ligands having specific steric and electronic properties. The amide ligands with bulky alkyl groups modify the catalyst's solubility characteristics and control the oligomerization selectivity, reducing wax and high molecular weight polyethylene production while maintaining catalytic activity.
Solution Approach 2:
The patent creates a composite catalyst system combining zirconium amide compound with specific organoaluminum compounds and additives. This composite approach enhances solubility in hydrocarbon solvents and provides synergistic effects that improve selectivity for desired oligomers while minimizing unwanted by-products.
2Quantity of substance
If zirconium tetrachloride is used with aluminum sesquichloride and triethyl aluminum, then linear alpha-olefins are produced, but selectivity for light alpha-olefins is relatively low and reaction temperature is high
Solution Approach 1:
The patent modifies the catalyst composition by using zirconium amide compounds instead of zirconium tetrachloride, combined with specific organoaluminum compounds. This parameter change in catalyst chemistry enables higher selectivity for light alpha-olefins (C4-C10) and allows operation at lower temperatures while maintaining high production rates.
Solution Approach 2:
The patent introduces specific organoaluminum compounds and additives as intermediaries that mediate the oligomerization process. These intermediaries control the catalyst's interaction with ethylene, directing the reaction pathway toward light alpha-olefins and improving overall selectivity.
3Productivity
If zirconium alkyl alkanoates are used as catalyst, then catalytic system is formed, but undesirable quantity of high molecular weight polyethylene is produced
Solution Approach 1:
The patent changes the ligand type from alkanoate to amide on the zirconium center. This parameter change fundamentally alters the catalyst's behavior, reducing the production of high molecular weight polyethylene while preserving oligomerization activity. The amide ligands provide better control over chain growth and termination.
4Manufacturing precision
If alcohol is used as third component in zirconium based catalyst system, then high purity alpha-olefin is produced, but polymer formation increases and C20+ fraction yield is high
Solution Approach 1:
The patent replaces the alcohol component with a specifically designed zirconium amide compound. This parameter change eliminates the need for alcohol additives while achieving high purity alpha-olefins. The amide ligands inherently provide better control over product distribution, reducing polymer formation and C20+ fraction.
5Manufacturing precision
If zirconium compound is mixed with ketals, acetals and hydrocarbyl-aluminum halide, then selectivity for light alpha-olefins is good, but activity is low and polymer traces accumulate causing reactor plugging
Solution Approach 1:
The patent creates an optimized composite catalyst system using zirconium amide compound combined with specific organoaluminum compounds and additives. This composite approach maintains high selectivity for light alpha-olefins while significantly improving catalytic activity and preventing polymer accumulation that causes reactor plugging.
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 purity and broad weight percent distribution of linear alpha-olefins from C4 to C16, with minimal polymer formation and improved reactor stability, enhancing the efficiency of ethylene oligomerization.
Implementation Method 1
reacting a zirconium component having formula ZrX m .nTHF with a substituted amide of formula RCONR'R'' to obtain a zirconium amide compound having formula ZrX m .n(RCONR'R'')
Implementation Method 2
catalyst composition for use as catalyst system for ethylene oligomerization, providing high activity and produce linear oligomer product
Data Source
AI summary
The present invention describes a catalyst composition for use as a catalyst system for an ethylene oligomerization, providing high activity and produce linear oligomer product having broad weight percent distribution i.e. C4 to C16. The catalyst composition comprises a zirconium amide compound, an organoaluminum compound and an additive. The present invention also provides a process for preparation of the zirconium amide compound comprising reacting a zirconium component having formula ZrXm.nTHF, wherein X is halogen atom; m is an integer having value equal or less than 4 and n is a number equal or less than 2, and a substituted amide of formula RCONR'R", wherein R, R' and R" are saturated or unsaturated aliphatic C1-C10 hydrocarbon or aromatic C6-C14 hydrocarbon, in the presence of an organic solvent.