Influence of Metal-Alkyls on Early-Stage Ethylene Polymerization over a Cr/SiO2 Phillips Catalyst: A Bulk Characterization and X-ray Chemical Imaging Study

Maarten K. Jongkind; Florian Meirer; Koen W. Bossers; Iris C. ten Have; Hendrik Ohldag; Benjamin Watts; Theo van Kessel; Nic Friederichs; Bert M. Weckhuysen

doi:10.1002/chem.202002632

Influence of Metal-Alkyls on Early-Stage Ethylene Polymerization over a Cr/SiO₂ Phillips Catalyst: A Bulk Characterization and X-ray Chemical Imaging Study

Maarten K. Jongkind, Florian Meirer, Koen W. Bossers, Iris C. ten Have, Hendrik Ohldag, Benjamin Watts, Theo van Kessel, Nic Friederichs, Bert M. Weckhuysen^*

^*Corresponding author for this work

Sub Inorganic Chemistry and Catalysis

Research output: Contribution to journal › Article › Academic › peer-review

Abstract

The Cr/SiO₂ Phillips catalyst has taken a central role in ethylene polymerization since its invention in 1953. The uniqueness of this catalyst is related to its ability to produce broad molecular weight distribution (MWD) PE materials as well as that no co-catalysts are required to attain activity. Nonetheless, co-catalysts in the form of metal-alkyls can be added for scavenging poisons, enhancing catalyst activity, reducing the induction period, and tailoring polymer characteristics. The activation mechanism and related polymerization mechanism remain elusive, despite extensive industrial and academic research. Here, we show that by varying the type and amount of metal-alkyl co-catalyst, we can tailor polymer properties around a single Cr/SiO₂ Phillips catalyst formulation. Furthermore, we show that these different polymer properties exist in the early stages of polymerization. We have used conventional polymer characterization techniques, such as size exclusion chromatography (SEC) and ¹³C NMR, for studying the metal-alkyl co-catalyst effect on short-chain branching (SCB), long-chain branching (LCB) and molecular weight distribution (MWD) at the bulk scale. In addition, scanning transmission X-ray microscopy (STXM) was used as a synchrotron technique to study the PE formation in the early stages: allowing us to investigate the produced type of early-stage PE within one particle cross-section with high energy resolution and nanometer scale spatial resolution.

Original language	English
Pages (from-to)	1688-1699
Number of pages	12
Journal	Chemistry - A European Journal
Volume	27
Issue number	5
DOIs	https://doi.org/10.1002/chem.202002632
Publication status	Published - 21 Jan 2021

Bibliographical note

Funding Information:
H. Meeldijk (Utrecht University, UU) is acknowledged for his help in depositing the catalyst materials onto the TEM grids. E. Troisi (SABIC, Geleen) is acknowledged for his help with the DSC measurements. T. Schoffelen (SABIC, Geleen) is acknowledged for providing the reference PE materials. B.M. Weckhuysen acknowledges the TKI Chemistry (Topconsortium voor Kennis en Innovatie Chemie) and SABIC for funding of this research project. This research used resources of the Advanced Light Source, a U.S. DOE Office of Science User Facility under contract no. DE-AC02-05CH11231. The PolLux end station was financed by the German Ministerium f?r Bildiung und Forschung (BMBF) through contracts 05K16WED and 05K19WE2.

Publisher Copyright:
© 2020 The Authors. Published by Wiley-VCH GmbH

Funding

H. Meeldijk (Utrecht University, UU) is acknowledged for his help in depositing the catalyst materials onto the TEM grids. E. Troisi (SABIC, Geleen) is acknowledged for his help with the DSC measurements. T. Schoffelen (SABIC, Geleen) is acknowledged for providing the reference PE materials. B.M. Weckhuysen acknowledges the TKI Chemistry (Topconsortium voor Kennis en Innovatie Chemie) and SABIC for funding of this research project. This research used resources of the Advanced Light Source, a U.S. DOE Office of Science User Facility under contract no. DE-AC02-05CH11231. The PolLux end station was financed by the German Ministerium f?r Bildiung und Forschung (BMBF) through contracts 05K16WED and 05K19WE2.

Keywords

chromium
Phillips catalyst
polyethylene crystallinity
polymerization catalysis
scanning transmission X-ray microscopy

Access to Document

10.1002/chem.202002632Licence: CC BY

Chemistry A European J - 2020 - Jongkind - Influence of Metal‐Alkyls on Early‐Stage Ethylene Polymerization over a Cr SiO2Final published version, 2.28 MBLicence: CC BY

Cite this

Jongkind, M. K., Meirer, F., Bossers, K. W., ten Have, I. C., Ohldag, H., Watts, B., van Kessel, T., Friederichs, N., & Weckhuysen, B. M. (2021). Influence of Metal-Alkyls on Early-Stage Ethylene Polymerization over a Cr/SiO₂ Phillips Catalyst: A Bulk Characterization and X-ray Chemical Imaging Study. Chemistry - A European Journal, 27(5), 1688-1699. https://doi.org/10.1002/chem.202002632

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title = "Influence of Metal-Alkyls on Early-Stage Ethylene Polymerization over a Cr/SiO2 Phillips Catalyst: A Bulk Characterization and X-ray Chemical Imaging Study",

abstract = "The Cr/SiO2 Phillips catalyst has taken a central role in ethylene polymerization since its invention in 1953. The uniqueness of this catalyst is related to its ability to produce broad molecular weight distribution (MWD) PE materials as well as that no co-catalysts are required to attain activity. Nonetheless, co-catalysts in the form of metal-alkyls can be added for scavenging poisons, enhancing catalyst activity, reducing the induction period, and tailoring polymer characteristics. The activation mechanism and related polymerization mechanism remain elusive, despite extensive industrial and academic research. Here, we show that by varying the type and amount of metal-alkyl co-catalyst, we can tailor polymer properties around a single Cr/SiO2 Phillips catalyst formulation. Furthermore, we show that these different polymer properties exist in the early stages of polymerization. We have used conventional polymer characterization techniques, such as size exclusion chromatography (SEC) and 13C NMR, for studying the metal-alkyl co-catalyst effect on short-chain branching (SCB), long-chain branching (LCB) and molecular weight distribution (MWD) at the bulk scale. In addition, scanning transmission X-ray microscopy (STXM) was used as a synchrotron technique to study the PE formation in the early stages: allowing us to investigate the produced type of early-stage PE within one particle cross-section with high energy resolution and nanometer scale spatial resolution.",

keywords = "chromium, Phillips catalyst, polyethylene crystallinity, polymerization catalysis, scanning transmission X-ray microscopy",

author = "Jongkind, {Maarten K.} and Florian Meirer and Bossers, {Koen W.} and {ten Have}, {Iris C.} and Hendrik Ohldag and Benjamin Watts and {van Kessel}, Theo and Nic Friederichs and Weckhuysen, {Bert M.}",

note = "Funding Information: H. Meeldijk (Utrecht University, UU) is acknowledged for his help in depositing the catalyst materials onto the TEM grids. E. Troisi (SABIC, Geleen) is acknowledged for his help with the DSC measurements. T. Schoffelen (SABIC, Geleen) is acknowledged for providing the reference PE materials. B.M. Weckhuysen acknowledges the TKI Chemistry (Topconsortium voor Kennis en Innovatie Chemie) and SABIC for funding of this research project. This research used resources of the Advanced Light Source, a U.S. DOE Office of Science User Facility under contract no. DE-AC02-05CH11231. The PolLux end station was financed by the German Ministerium f?r Bildiung und Forschung (BMBF) through contracts 05K16WED and 05K19WE2. Publisher Copyright: {\textcopyright} 2020 The Authors. Published by Wiley-VCH GmbH",

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Jongkind, MK, Meirer, F, Bossers, KW, ten Have, IC, Ohldag, H, Watts, B, van Kessel, T, Friederichs, N & Weckhuysen, BM 2021, 'Influence of Metal-Alkyls on Early-Stage Ethylene Polymerization over a Cr/SiO₂ Phillips Catalyst: A Bulk Characterization and X-ray Chemical Imaging Study', Chemistry - A European Journal, vol. 27, no. 5, pp. 1688-1699. https://doi.org/10.1002/chem.202002632

Influence of Metal-Alkyls on Early-Stage Ethylene Polymerization over a Cr/SiO₂ Phillips Catalyst: A Bulk Characterization and X-ray Chemical Imaging Study. / Jongkind, Maarten K.; Meirer, Florian; Bossers, Koen W. et al.
In: Chemistry - A European Journal, Vol. 27, No. 5, 21.01.2021, p. 1688-1699.

Research output: Contribution to journal › Article › Academic › peer-review

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AU - Meirer, Florian

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KW - chromium

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KW - polymerization catalysis

KW - scanning transmission X-ray microscopy

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