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The Role of Catalyst Support, Diluent and Co-Catalyst in Chromium-Mediated Heterogeneous Ethylene Trimerisation

Lamb, M.J.; Apperley, D.C.; Watson, M.J.; Dyer, P.W.

The Role of Catalyst Support, Diluent and Co-Catalyst in Chromium-Mediated Heterogeneous Ethylene Trimerisation Thumbnail


Authors

M.J. Lamb

D.C. Apperley

M.J. Watson



Abstract

Sequential treatment of a previously-calcined solid oxide support (i.e. SiO2, γ-Al2O3, or mixed SiO2–Al2O3) with solutions of Cr{N(SiMe3)2}3 (0.71 wt% Cr) and a Lewis acidic alkyl aluminium-based co-catalyst (15 molar equivalents) affords initiator systems active for the oligomerisation and/or polymerisation of ethylene. The influence of the oxide support, calcination temperature, co-catalyst, and reaction diluent on both the productivity and selectivity of the immobilised chromium initiator systems have been investigated, with the best performing combination (SiO2−600, modified methyl aluminoxane-12 {MMAO-12}, heptane) producing a mixture of hexenes (61 wt%; 79% 1-hexene), and polyethylene (16 wt%) with an activity of 2403 g gCr−1 h−1. The observed product distribution is rationalised by two competing processes: trimerisation via a supported metallacycle-based mechanism and polymerisation through a classical Cossee-Arlman chain-growth pathway. This is supported by the indirect observation of two distinct chromium environments at the surface of the oxide support by a solid-state 29Si NMR spectroscopic study of the Cr{N(SiMe3)2}x/SiO2−600 pro-initiator.

Citation

Lamb, M., Apperley, D., Watson, M., & Dyer, P. (2018). The Role of Catalyst Support, Diluent and Co-Catalyst in Chromium-Mediated Heterogeneous Ethylene Trimerisation. Topics in Catalysis, 61(3-4), 213-224. https://doi.org/10.1007/s11244-018-0891-8

Journal Article Type Article
Online Publication Date Jan 16, 2018
Publication Date Apr 1, 2018
Deposit Date Jan 31, 2018
Publicly Available Date Mar 29, 2024
Journal Topics in Catalysis
Print ISSN 1022-5528
Electronic ISSN 1572-9028
Publisher Springer
Peer Reviewed Peer Reviewed
Volume 61
Issue 3-4
Pages 213-224
DOI https://doi.org/10.1007/s11244-018-0891-8

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Copyright Statement
Advance online version © The Author(s) 2018.
This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.





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