Cationic Pyridylamido Adsorbate on Brønsted Acidic Sulfated Zirconia: A Molecular Supported Organohafnium Catalyst for Olefin Homo- and Co-Polymerization

Jialong Zhang, Alessandro Motta, Yanshan Gao, Madelyn Marie Stalzer, Massimiliano Delferro, Boping Liu, Tracy L. Lohr, Tobin J Marks

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

Here we report the combined application of high-resolution solid-state 13C-CPMAS-NMR and FT-IR spectroscopy, elemental analysis, kinetic poisoning/active site counting, variable dielectric constant medium, and DFT computation to characterize the surface chemistry of a pyridylamido hafnium complex (Cat1, L1-HfMe2, L1 = 2,6-diisopropyl-N-{(2-isopropylphenyl)[6-(naphthalen-1-yl)pyridin-2-yl]methyl}aniline) adsorbed on Brønsted acidic sulfated zirconia (ZrS). The spectroscopic and DFT results indicate protonolytic formation of organohafnium cations having a largely electrostatic pyridylamido-Hf-CH3 +···ZrS- interaction with elongated Hf···OZrS distances of ∼2.14 Å. High-molecular-weight polyethylenes and ethylene/1-octene copolymers are obtained with this supported catalyst without an activator/cocatalyst. The DFT calculations reveal that the first ethylene insertion into the Hf-methyl bond has a lower barrier than the corresponding insertion into the Hf-aryl bond of this single-site heterogeneous catalyst.

Original languageEnglish
Pages (from-to)4893-4901
Number of pages9
JournalACS Catalysis
Volume8
Issue number6
DOIs
Publication statusPublished - Jun 1 2018

Keywords

  • DFT calculations
  • olefin polymerization
  • organohafnium catalyst
  • sulfated oxides
  • supported catalysts

ASJC Scopus subject areas

  • Catalysis

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