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Effects of Alkyl Aluminum on SiO 2 ‐Supported Silyl‐Chromate(Cr)/Imido‐Vanadium(V) Bimetallic Catalysts for Producing Bimodal Polyethylene
Author(s) -
Liu Bangming,
Zhao Ning,
Jin Yulong,
Cheng Ruihua,
He Xuelian,
Liu Zhen,
Liu Boping
Publication year - 2017
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.201700006
Subject(s) - bimetallic strip , alkyl , catalysis , vanadium , polymerization , polyethylene , comonomer , polymer chemistry , materials science , polymer , ethylene , chemistry , inorganic chemistry , organic chemistry
SiO 2 ‐supported Cr–V bimetallic catalyst can be used for producing bimodal polyethylene which can be applied for high‐performance pipe material. Alkyl aluminum are used to prereduce the bimetallic catalysts, and the effects of alkyl aluminum for the bimetallic catalyst are fully studied by catalyst characterization, polymerization kinetics, and the properties of polymer product by the comparison with the catalyst without prereduction. The result shows that the optimum polymerization activity is almost double after the catalyst is prereduced by triisobutylaluminum (TIBA), and the needed dosage of alkyl aluminum also is decreased significantly. The alkyl aluminum of the prereduced catalyst can also act as a chain transfer agent, significantly reducing the molecular weight of the polymer. The diethylaluminum chloride (DEAC) is mostly deactivating the Cr species during the ethylene polymerization. The synthesized catalysts, prereduced by TIBA, triethylaluminum (TEA), and DEAC, all exhibited good hydrogen response and comonomer interposition ability, which will be favorable for the further application of the bimetallic catalyst in the industrial field.