Binary Mixtures (AlknAlCl3–n + Alk2Mg) as Catalyst Components for Ethylene Polymerization and the Role of Titanium Oxidation State in Their Catalytic Activity

It was shown by EPR spectroscopy that Ti(IV) was gradually reduced to Ti(III) when a titanium(IV) dichloride complex with a saligenin ligand was used as a model pre-catalyst in the presence of (Et n AlCl 3– n + Bu 2 Mg) as an activator. Pre-activation of this complex (by stirring in an inert atmosph...

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Published inPetroleum chemistry Vol. 64; no. 6; pp. 706 - 716
Main Authors Tuskaev, V. A., Kurmaev, D. A., Gagieva, S. Ch, Evseeva, M. D., Buzin, M. I., Golubev, E. K., Bulychev, B. M.
Format Journal Article
LanguageEnglish
Published Moscow Pleiades Publishing 01.06.2024
Springer Nature B.V
Subjects
Aluminum
Binary mixtures
Catalysts
Catalytic activity
Chemical synthesis
Chemistry
Chemistry and Materials Science
Dichlorides
Industrial Chemistry/Chemical Engineering
Inert atmospheres
Magnesium
Organometallic compounds
Oxidation
Titanium
Titanium compounds
Valence
titanium(III)
titanium(IV)
ultrahigh-molecular-weight polyethylenen
post-metallocenes
pre-activation
Al/Mg activators
ethylene polymerization
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Summary:It was shown by EPR spectroscopy that Ti(IV) was gradually reduced to Ti(III) when a titanium(IV) dichloride complex with a saligenin ligand was used as a model pre-catalyst in the presence of (Et n AlCl 3– n + Bu 2 Mg) as an activator. Pre-activation of this complex (by stirring in an inert atmosphere with a half-load of the Al/Mg activator before being introduced into the reactor) significantly (about twofold) enhanced its catalytic activity, up to 4100 kg PE mol Ti –1 h –1 atm –1 . All the synthesized polyethylene samples were linear ultrahigh-molecular-weight polymers (UHMWPEs) with M v = 1.0–3.5×10 6 g/mol. This pre-activation technique was further employed to test a series of Al/Mg activators that differed in the nature of their organometallic compounds and in their Al/Mg molar ratio. The test data suggest that the catalytic system under study had active sites with titanium being present mainly in the oxidation state of +3. Most samples of UHMWPE produced with the pre-activated complex proved suitable for solvent-free processing into high-strength oriented films.
ISSN:0965-5441
1555-6239
DOI:10.1134/S0965544124040054