Titanium-based phenoxy-imine catalyst for selective ethylene trimerization: effect of temperature on the activity, selectivity and properties of polymeric side products

Catalysis Science & Technology

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 kg_1-hexene g_Ti−¹ h−¹) between 30 and 40 °C, to a moderate polyethylene formation (70–80 wt%, 60–70 kg_polyethylene g_Ti−¹ h−¹) at a 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 ¹³C NMR analyses, polyethylenes were found to exhibit high molar masses (>10⁵ 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 a higher temperature. The increase of dispersity to 4.6 at 80 °C suggests a change from single to multi-site catalysis. The poor comonomer incorporation ability of the active species is reminiscent of a molecular Ziegler–Natta or a bulky post-metallocene catalyst.

For details: Titanium-based phenoxy-imine catalyst for selective ethylene trimerization: effect of temperature on the activity, selectivity and properties of polymeric side products

Astrid Cordier ^a, Pierre-Alain Breuil ^b, Typhène Michel ^b ,Lionel Magna ^b, Hélène Olivier-Bourbigou ^b, Jean Raynaud ^a, Christophe Boisson ^a and Vincent Monteil ^a

^a UMR 5265, Laboratoire de Chimie Catalyse Polymères et Procédés (C2P2), Univ. Lyon, Université Claude Bernard Lyon 1, CPE Lyon, CNRS, Bat 308F, 43 Bd du 11 novembre 1918, 69616 Villeurbanne, France

^b IFP Energies nouvelles, Rond-point de l'échangeur de Solaize, 69360 Solaize, France

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Catalysis Science & Technology
https://doi.org/10.1039/C9CY02056J
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