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Preparation of Extremely Active Ethylene Tetramerization Catalyst [iPrN(PAr2)2−CrCl2]+[B(C6F5)4]– (Ar = −C6H4-p-SiR3)
- Author(s)
- 이정현
- Advisor
- 이분열
- Department
- 일반대학원 분자과학기술학과
- Publisher
- The Graduate School, Ajou University
- Publication Year
- 2022-02
- Language
- eng
- Keyword
- 1-octene production; Ethylene tetramderization; bis(phosphine)ligand; chromium catalyst; tetrakis(pentafluorophenyl)borate
- Alternative Abstract
- Numerous efforts have been made to achieve “on-purpose” 1-octene production since Sasol discovered a Cr-based selective ethylene tetramerization catalyst in the early 2000s. By preparing a series of bis(phosphine) ligands iPrN(PAr2)2 where the Ar contains a bulky –SiR3 substituent (Ar = -C6H4-p-Si(nBu)3 (1), -C6H4-p-Si(1-hexyl)3 (2), -C6H4-p-Si(1-octyl)3 (3), -C6H4-p-Si(2-ethylhexyl)3 (4), -C6H4-p-Si(3,7-dimethyloctyl)3 (5)), we obtained an extremely active catalyst that meets the criteria for commercial utilization. The Cr complexes [iPrN(PAr2)2-CrCl2]+[B(C6F5)4]–, obtained by reacting ligands 1-5 with [(CH3CN)4CrCl2]+[B(C6F5)4]–, showed high activity exceeding 6000 kg/g-Cr/h, when combined with the inexpensive iBu3Al, thus avoiding the use of expensive modified methylaluminoxane (MMAO). The bulky –SiR3 substituents played a key role in the success of catalysis by blocking the formation of inactive species (Cr complexes coordinated by two iPrN(PAr2)2 ligands, that is, [(iPrN(PAr2)2)2-CrCl2]+[B(C6F5)4]–). Among the complexes prepared, [3-CrCl2]+[B(C6F5)4]– exhibited the highest activity (11,100 kg/g-Cr/h, 100 kg/g-catalyst) with high 1-octene selectivity (75 wt%), and, moreover, mitigated the generation of undesired > C10 fractions (10.7 wt%). A 10-g-scale synthesis of 3 was developed, as well as a facile and low-cost synthetic method for [(CH3CN)4CrCl2]+[B(C6F5)4]–.
- Fulltext
- Appears in Collections:
- Graduate School of Ajou University > Department of Molecular Science and Technology > 3. Theses(Master)
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