文献类型：期刊文献

英文题名：Cationic Pyridylamido Adsorbate on Br?nsted Acidic Sulfated Zirconia: A Molecular Supported Organohafnium Catalyst for Olefin Homo- and Co-Polymerization

作者：Zhang, Jialong[1,2]; Motta, Alessandro[3]; Gao, Yanshan[2]; Stalzer, Madelyn Marie[2]; Delferro, Massimiliano[2]; Liu, Boping[1]; Lohr, Tracy L.[2]; Marks, Tobin J.[2]

机构：[1] State Key Laboratory of Chemical Engineering, East China University of Science and Technology, Shanghai, 200237, China; [2] Department of Chemistry, Northwestern University, Evanston, IL, 60208, United States; [3] Dipartimento di Scienze Chimiche, Università di Roma la Sapienza, INSTM, UdR Roma, Roma, I-00185, Italy

年份：2018

卷号：8

期号：6

起止页码：4893

外文期刊名：ACS Catalysis

收录：EI(收录号：20181905152112)

语种：英文

外文关键词：Catalyst supports - Density functional theory - Zirconia - Cationic polymerization - Polyethylenes - Chemical analysis - Ethylene - Nuclear magnetic resonance spectroscopy - Hafnium compounds - Aniline

摘要：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 Br?nsted 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 ?. 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. ? 2018 American Chemical Society.