Chromium Catalyst for Olefin Trimerization and Tetramerization
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Solution Overview
Problem
Existing olefin oligomerization catalyst systems are limited to trimerization and lack the capability for tetramerization, requiring complex solvent removal processes that reduce catalyst stability and selectivity, and are costly due to high comonomer prices in producing LLDPE.
Innovation Solution
A novel catalyst system comprising a ligand compound, a chromium compound, and an aliphatic or alicyclic hydrocarbon solvent, allowing for both trimerization and tetramerization of olefins with improved stability and selectivity, using a specific molar ratio and solvent composition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a catalyst system is prepared in an unsaturated hydrocarbon solvent, then catalytic activity is improved, but the solvent must be removed by vacuum decompression and the process complexity increases
Solution Approach 1:
The patent changes the solvent parameter from unsaturated hydrocarbon to saturated hydrocarbon, which fundamentally alters the catalyst preparation process. This parameter change eliminates the need for vacuum decompression and black precipitate filtration while maintaining high catalytic activity, thus resolving the contradiction between activity and process complexity
2Device complexity
If the catalyst is prepared in a saturated hydrocarbon solvent, then the solvent removal process is simplified, but thermal stability is lowered and catalyst selectivity decreases
Solution Approach 1:
The patent uses a composite catalyst system comprising Cr(EH)3, pyrrole compound, and aluminum alkyl in saturated hydrocarbon solvent. This composite formulation enhances thermal stability and selectivity despite using a simpler saturated hydrocarbon solvent, resolving the contradiction between process simplicity and catalyst reliability
3Device complexity
If only trimerization is conducted, then the catalyst system is simpler, but the versatility of olefin oligomerization is limited
Solution Approach 1:
The patent modifies the catalyst system to perform multiple functions - it can conduct both trimerization and tetramerization of olefins. The addition of specific ligands and adjustment of aluminum alkyl compounds enable the same catalyst system to produce different oligomer products (C6 and C8), thus achieving versatility without proportionally increasing system complexity
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 enables high activity and selectivity in producing 1-hexene and 1-octene, reducing production costs and eliminating the need for solvent removal processes, thereby enhancing the efficiency and commercial viability of olefin oligomerization.
Implementation Method 1
a catalyst system for olefin oligomerization including: a ligand compound; a chromium compound; a metal alkyl compound; and an aliphatic or alicyclic hydrocarbon solvent
Data Source
AI summary
Disclosed are a catalyst system capable of selectively oligomerizing olefins including ethylene and a method for preparing an olefin oligomer by using the same and, specifically, a novel catalyst system capable of trimerizing and tetramerizing olefins, unlike olefin oligomerization catalyst systems that have been reported so far, and a method for preparing an olefin oligomer by using the same. The present invention provides a catalyst system for olefin oligomerization, the catalyst system comprising: a ligand compound represented by chemical formula 1 or 2; a chromium compound; a metal alkyl compound; and an aliphatic or alicyclic hydrocarbon solvent.