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Silsesquioxane‐Supported Chromium Catalyst for Insight into Phillips‐Type Ethylene Polymerization
Author(s) -
Zeng Yanning,
Liu Shuxin,
Terano Minoru
Publication year - 2018
Publication title -
macromolecular reaction engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.37
H-Index - 32
eISSN - 1862-8338
pISSN - 1862-832X
DOI - 10.1002/mren.201800049
Subject(s) - silsesquioxane , polymerization , hexavalent chromium , polymer chemistry , chromium , catalysis , polyethylene , ethylene , branching (polymer chemistry) , chemistry , copolymer , materials science , organic chemistry , polymer
Abstract To investigate the Phillips catalyst for ethylene polymerization, a family of silsesquioxane‐supported chromium catalysts with a bipodal structure have been synthesized from trivalent or hexavalent chromium precursor and fully characterized by 1 H/ 13 C/ 29 Si NMR, FT‐IR, and UV–vis spectroscopies. Upon activation with tri‐ n ‐octylaluminum or butylated hydroxytoluene (BHT) modified TIBA following the “TIBA‐BHT”, all the silsesquioxane‐supported chromium catalysts display moderate activities (50–523 g‐PE•g‐cat −1 ·h −1 ) for ethylene polymerization, producing polyethylene (PE) with high methyl branching level (0.1–1.3/1000C) and a clear bimodal molecular weight distribution (MWD). Catalysts with hexavalent chromium precursor exhibit higher activities than trivalent ones. The type of activator and coordination environments of the active site play a key role in the MWD of obtained PE.