Titanium Catalyst Lewis Base Mediator for Ethylene Dimerization
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Solution Overview
Problem
Catalytic systems based on titanium for the selective dimerization of ethylene to 1-butene suffer from significant polyethylene formation, leading to catalyst deactivation and operational challenges in industrial processes.
Innovation Solution
A catalytic composition is developed by mixing an alkoxy or aryloxy titanium compound with a preformed mixture of a Lewis base type additive and an aluminium compound in stoichiometric proportions, limiting the generation of catalytic species responsible for polyethylene production, thereby reducing or eliminating polyethylene formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If titanium-based catalytic systems are used for ethylene dimerization, then high selectivity for 1-butene is achieved, but significant polyethylene formation occurs leading to catalyst deactivation
Solution Approach 1:
A Lewis base compound is introduced as an intermediary substance that mediates between the titanium catalyst and ethylene reactant. The Lewis base forms a complex with the titanium center, modifying its electronic properties and steric environment to favor dimerization over polymerization, thereby resolving the contradiction between selectivity and catalyst stability
Solution Approach 2:
The invention changes the chemical parameter of the catalyst system by adding a Lewis base compound, which alters the electronic and steric parameters of the titanium center. This parameter modification shifts the reaction pathway selectivity toward dimerization while suppressing polymerization, thus improving both selectivity and catalyst reliability
2Productivity
If conventional titanium catalysts with trialkylaluminium are used, then dimerization activity is maintained, but polyethylene formation increases causing operational difficulties
Solution Approach 1:
The invention converts the harmful effect of high titanium reactivity (which causes polymerization) into a beneficial effect by introducing a Lewis base. The Lewis base selectively modifies the titanium center to enhance dimerization activity while suppressing unwanted polymerization, thus converting the harmful high reactivity into a beneficial selective catalysis
Solution Approach 2:
The Lewis base acts as an intermediary that selectively interacts with the titanium catalyst to modulate its activity. This intermediary substance enables high dimerization productivity while minimizing polyethylene formation, resolving the contradiction between productivity and harmful byproduct generation
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 solution achieves high selectivity and activity for ethylene dimerization to 1-butene with near-zero polyethylene production, enhancing the operational stability and efficiency of the process.
Implementation Method 1
a catalytic composition obtained by mixing an alkoxy or aryloxy titanium compound with a preformed mixture of a Lewis base type additive and an aluminium compound
Implementation Method 2
selective dimerization of ethylene to 1-butene using said catalytic composition
Data Source
AI summary
The invention describes a catalytic composition obtained by interaction of an alkyl titanate on the one hand with a preformed mixture of an alkylaluminium and a Lewis base on the other hand. The invention also describes the use of said composition in a process for the selective dimerization of ethylene to 1-butene.