Formation of isolated titanium(III) ions in superactive titanium–magnesium catalysts with a low titanium content as active sites in ethylene polymerization

Superactive supported titanium–magnesium catalysts (TMCs) with a low titanium content (≤0.1wt.%), in distinction to conventional TMCs (≥1wt.%), were shown to interact with AlR3 of different compositions to produce compounds with a high (30–70%) concentration of isolated (ESR visible) Ti3+ ions. For...

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Bibliographic Details
Published in:Catalysis communications 2014-03, Vol.48, p.38-40
Main Authors: Koshevoy, Evgeny I., Mikenas, Tatiana B., Zakharov, Vladimir A., Volodin, Alexander M., Kenzhin, Roman M.
Format: Article
Language:English
Subjects:
Active sites
Activity
EPR/ESR
Ziegler–Natta polymerization
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Summary:Superactive supported titanium–magnesium catalysts (TMCs) with a low titanium content (≤0.1wt.%), in distinction to conventional TMCs (≥1wt.%), were shown to interact with AlR3 of different compositions to produce compounds with a high (30–70%) concentration of isolated (ESR visible) Ti3+ ions. For the first time a correlation between the content of isolated Ti3+ species in these catalysts and activity in ethylene polymerization was found. Activation of titanium–magnesium catalysts with a low Ti content by AlR3 leads to formation of active sites from isolate Ti(III) compounds. [Display omitted] •Isolated Ti3+ compounds are formed in superactive TMCs with a low Ti content.•The fraction of isolated Ti(III) compounds reaches 70% of total titanium content.•A correlation was found between catalyst activity and content of isolated Ti3+ ions.
ISSN:1566-7367
1873-3905
DOI:10.1016/j.catcom.2014.01.015