Introduction of titanium species into fluorine-modified SiO2- supported Cr-V bimetallic catalyst for ethylene polymerization and ethylene/1-hexene copolymerization
Journal Title: Polyolefins Journal - Year 2017, Vol 4, Issue 2
Abstract
Chromium-vanadium (Cr-V) bimetallic catalysts are prepared by the introduction of vanadium into the Phillips catalyst which is one of the most significant industrial ethylene polymerization catalysts for tuning the Phillips catalyst performances and improving polyethylene properties. In the present work, titanium species were introduced into the fluorine-modified chromium-vanadium bimetallic catalysts (Cr-V-F) and the prepared catalysts were systematically explored. The element content results of multi-component catalysts showed that a competitive inhibition interaction existed between chromium and vanadium, whereas chromium was more preferable to attach to the Ti-SiO2 than vanadium. In addition, ethylene homopolymerization and ethylene/1-hexene copolymerization were carried out and examined with different catalysts. The introduction of titanium into fluorine-modified bimetallic catalysts enhanced the molecular weight (MW) and broadened the molecular weight distribution (MWD) of polyethylene. The MW of the titanium- and fluorine-modified bimetallic catalysts (Cr-V-F/Ti) firstly rose up and then dropped down with the increasing of the Al/Cr molar ratio. The Cr-V-F/Ti catalysts showed slightly depressed hydrogen response and incorporation of 1-hexene. The short-chain branch distribution (SCBD) results, which were characterized by TREF/SSA, showed that the introduction of the titanium species increased the SCB content in low MW fractions and decreased the SCB content in the high Mw fractions of ethylene/1-hexene copolymers obtained from (Cr-V-F/3Ti)600 in contrast to that from (Cr-V-F)600.
Authors and Affiliations
Qiaoqiao Sun, Ruihua Cheng, Zhen Liu, Xuelian He, Ning Zhao, Boping Liu
Keywords
Related Articles
- EP ID EP283178
- DOI 10.22063/POJ.2017.1464
- Views 143
- Downloads 0
Synthesis and identifcation of polystyrene via conventional and controlled radical polymerization methods: Effect of temperature, initiator and transfer agent on molecular weight and reaction rate
Polystyrene (PSt) has been known as one of the important polymers with a wide range of applications. Ability to synthesize PSt with different but predictable molecular weights for various applications is very important i...
Tuning the short chain branch distribution of ethylene and 1-hexene copolymers by SiO2-supported silyl chromate catalyst with different Al-alkyl co-catalysts
SiO2-supported silyl chromate catalyst is an important industrial catalyst for production of high grade HDPE pipe materials. The control of the short chain branch (SCB) distribution using this catalyst system is still a...
Thermal-insulation performance of low density polyethylene (LDPE) foams: Comparison between two radiation thermal conductivity models
The loss of energy, especially in industrial and residential buildings is one of the main reasons of increased energy consumption. Improving the thermal insulation properties of materials is a fundamental method for redu...
Reaction dynamics during the testing of polymerization catalyst
The olefins polymerization process in a slurry reactor is discussed. The reaction rate dynamics was analyzed and the contributions of feed flow, gas-liquid mass transfer, polymerization reaction, and catalyst deactivatio...
Embedding neat and carboxylated nanodiamonds into polypropylene membranes to enhance antifouling properties
The aim of the present work is to enhance the antifouling properties of polypropylene (PP) membrane based on hydrophilicity improvement. Different contents of neat and modifed nanodiamond (0.25, 0.50, 0.75 and 1.00 wt.%)...