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Titanium-based phenoxy-imine catalyst for selective ethylene trimerization: effect of temperature on the activity, selectivity and properties of polymeric side products
Titanium-based phenoxy-imine catalyst for selective ethylene trimerization: effect of temperature on the activity, selectivity and properties of polymeric side products
- Source :
- Catalysis Science & Technology, Catalysis Science & Technology, Royal Society of Chemistry, 2020, 10 (6), pp.1602-1608. ⟨10.1039/C9CY02056J⟩
- Publication Year :
- 2020
- Publisher :
- HAL CCSD, 2020.
-
Abstract
- International audience; The reactivity of a phenoxy-imine-ether system (FI)TiCl3/MAO was studied toward selective ethylene trimerization. This system was shown to either trimerize or polymerize ethylene depending on the reaction temperature. Its selectivity switches from a significant production of the trimerization product, 1-hexene (85 wt %, 520-450 kg1-hexene gTi-1 h-1) between 30 and 40 °C, to a moderate polyethylene formation (70-80 wt %, 60-70 kgpolyethylene gTi-1 h-1) at higher reaction temperature (T > 60 °C). Polymerization was investigated based on an original "polymer-to-catalyst" strategy aiming at identifying the active species responsible for this side reaction. Using DSC, SEC and high temperature 13 C NMR analyses, polyethylenes were found to exhibit high molar masses (> 10 5 g mol-1) and a low 1-hexene content (< 1 mol %) at any temperature. Kinetic studies support that trimerization and polymerization species are generated from the catalyst precursor at 40 °C but a parallel process may occur at higher temperature. The increase dispersity to 4.6 at 80 °C suggests a change from single to multisite catalysis. The poor comonomer incorporation ability of the active species is reminiscent of a molecular Ziegler Natta or a bulky postmetallocene catalyst.
Details
- Language :
- English
- ISSN :
- 20444753
- Database :
- OpenAIRE
- Journal :
- Catalysis Science & Technology, Catalysis Science & Technology, Royal Society of Chemistry, 2020, 10 (6), pp.1602-1608. ⟨10.1039/C9CY02056J⟩
- Accession number :
- edsair.doi.dedup.....453a161e9c73d6cada9e61c1f4f9a42d
- Full Text :
- https://doi.org/10.1039/C9CY02056J⟩