Active Sites in Cr(III)-Based Ethylene Polymerization Catalysts from Machine-Learning-Supported XAS and EPR Spectroscopy
Abstract
The ethylene polymerization Phillips catalyst has been employed for decades and is central to the polymer industry. While Cr(III) alkyl species are proposed to be the propagating sites, there is so far no direct experimental evidence for such proposal. In this work, by coupling Surface organometallic chemistry, EPR spectroscopy, and machine learning-supported XAS studies, we have studied the electronic structure of well-defined silica-supported Cr(III) alkyls and identified the presence of several surface species in high and low-spin states, associated with different coordination environments. Notably, low-spin Cr(III) sites are shown to participate in ethylene polymerization, indicating that similar Cr(III) alkyl species could be involved in the related Phillips catalyst. Show more
Permanent link
https://doi.org/10.3929/ethz-b-000648016Publication status
publishedExternal links
Journal / series
Angewandte Chemie. International EditionVolume
Pages / Article No.
Publisher
Wiley-VCHSubject
EPR Spectroscopy; Ethylene Polymerization; Heterogenous Catalysis; Machine Learning; Surface ChemistryFunding
192050 - Molecular Approach and Understanding in Heterogeneous Catalysis (SNF)
169134 - Molecular Approach to Heterogeneous Catalysis (SNF)
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