Publication Date:
2019
Description:
〈p〉Publication date: December 2019〈/p〉
〈p〉〈b〉Source:〈/b〉 Journal of Physics and Chemistry of Solids, Volume 135〈/p〉
〈p〉Author(s): Takahiro Iijima, Tadashi Shimizu, Atsushi Goto, Kenzo Deguchi, Toshihito Nakai, Ryutaro Ohashi, Masayoshi Saito〈/p〉
〈div xml:lang="en"〉
〈h5〉Abstract〈/h5〉
〈div〉〈p〉In Ti-based Ziegler-Natta catalysts (ZNCs), disagreements exist concerning which lateral surface of the MgCl〈sub〉2〈/sub〉 support adsorbs Ti species so as to be an active site for the catalysis of polymerization. In the present paper, we investigated the local structure of TiCl〈sub〉4〈/sub〉 adsorbed onto the surface of MgCl〈sub〉2〈/sub〉 by 〈sup〉47,49〈/sup〉Ti solid-state nuclear magnetic resonance (NMR) spectra at 21.8 T along with density functional theory (DFT) calculations. The magic-angle-spinning NMR spectrum of the TiCl〈sub〉4〈/sub〉/MgCl〈sub〉2〈/sub〉 adduct sample prepared by 20 h of milling, which exhibited broadened and shifted peaks compared to that of the sample without milling, was simulated by a Czjzek model considering the distribution of quadrupole interaction parameters. The electric field gradient and chemical shielding tensors of 〈sup〉49〈/sup〉Ti were obtained via DFT calculations for model molecules of TiCl〈sub〉4〈/sub〉, 2TiCl〈sub〉4〈/sub〉, and Ti〈sub〉2〈/sub〉Cl〈sub〉8〈/sub〉 adsorbed onto the (110), (104), and (104)-step defect surfaces of MgCl〈sub〉2〈/sub〉. By comparing the obtained NMR parameters, the 〈sup〉47,49〈/sup〉Ti NMR spectrum of the milled sample was assigned to TiCl〈sub〉4〈/sub〉 adsorbed onto the (104) surface of MgCl〈sub〉2〈/sub〉, which may not be a principal component of adsorption.〈/p〉〈/div〉
〈/div〉
〈h5〉Graphical abstract〈/h5〉
〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S002236971930472X-fx1.jpg" width="380" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉
Print ISSN:
0369-8726
Electronic ISSN:
1879-2553
Topics:
Chemistry and Pharmacology
,
Physics
