Role of Titanium in Ti/SiO2-Supported Metallocene-based Olefin Polymerization Catalysts. Part 1: Genesis of Active Sites and Catalytic Performance

Silvia Zanoni, Alexandre Welle, Virginie Cirriez, Bert M. Weckhuysen*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

Performance enhancement of metallocene-based olefin polymerization catalysts can be obtained, among others, by the chemical modification of their support. We investigated a titanated SiO2 (Ti/SiO2) as an improved support material for zirconocene catalysts, which lead to ∼35 % higher ethylene polymerization yields when compared to the unmodified SiO2-supported metallocene. The improved catalytic performance of the modified catalyst was found to be related to the presence of a Ti-based active site, second to the Zirconocene centers, as well as to a higher Lewis acidity in the titanated supported-MAO, which improved the activation of the Zr-based centers. The Ti active species were generated by reduction of the Ti/SiO2 support with the methylaluminoxane (MAO) co-catalysts, which introduced oxygen vacancies (VO) and Ti3+ species, as confirmed by probe molecule Fourier Transform Infrared (FT-IR) spectroscopy and UV-Vis Diffuse Reflectance Spectroscopy (DRS). The higher Lewis acidity was linked to 5-coordinated Ti4+, as detected by probe molecules FT-IR spectroscopy.

Original languageEnglish
Article numbere202300221
Pages (from-to)1-15
Number of pages16
JournalChemCatChem
Volume15
Issue number10
Early online dateMay 2023
DOIs
Publication statusPublished - 19 May 2023

Bibliographical note

Publisher Copyright:
© 2023 The Authors. ChemCatChem published by Wiley-VCH GmbH.

Funding

Laura de Kort (Utrecht University, UU) is acknowledged for performing the DSC measurements. Peter de Peinder (UU) and Alessandro Piovano (University of Turin) are thanked for the useful discussion on the infrared spectroscopy data interpretation. Nikolaos Nikolopoulos (UU) is thanked for the fruitful discussion and the UV‐Vis‐DRS measurements. Guusje Delen (UU) is thanked for the feedback on the text revision. Coen Mulder and Helen de Waard (UU) are acknowledged for performing the ICP‐OES experiments. The authors acknowledge project funding from TotalEnergies.

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    Keywords

    • IR spectroscopy
    • catalyst
    • metallocene
    • polymerization
    • titania

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