Homogeneous Tandem Catalysis of Bis(2-decylthioethyl)amine−Chromium Trimerization Catalyst in Combination with Metallocene Catalysts

Wet-Roos, Deon De; Dixon, J

doi:10.1021/ma048153k

Cited by 38 publications

(25 citation statements)

References 11 publications

(16 reference statements)

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“…They discovered that this unusually high 1-octene selectivity was caused by the unique extended metallacyclic mechanism in operation. 1-Octene was formed by further insertion of ethylene into a seven-membered metallacycloheptane intermediate, whereas 1-hexene was formed by elimination from this species as in other reported trimerization reactions [24,36,[45][46][47].…”

Section: Mechanism Of Ethylene Tetramerizationsupporting

confidence: 52%

Recent Research Progress in Preparation of Ethylene Oligomers with Chromium-Based Catalytic Systems

Zhu

Wang

2011

Designed Monomers and Polymers

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Ethylene oligomers, notably 1-hexene and 1-octene, are usually used as co-monomers in the production of linear low-density polyethylene (LLDPE). Because of the great value of 1-hexene and 1-octene, there have been many reports on the selective oligomerization of ethylene to 1-hexene and 1-octene recently. Research of ethylene oligomerization focuses mainly on the synthesis of catalysts and the mechanism of oligomerization. Much of this research concerns investigation into a catalytic system that can oligomerize ethylene to 1-hexene or 1-octene with high selectivity and activity. Different kinds of catalysts have been synthesized to catalyze the reactions, and the chromium-based homogeneous catalysts are found to be the most suitable ones. This article reviews the recent research progress in synthesis of chromium catalyst systems and study on the mechanism of ethylene oligomerization catalyzed by these catalysts.

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Section: Mechanism Of Ethylene Tetramerizationsupporting

confidence: 52%

Recent Research Progress in Preparation of Ethylene Oligomers with Chromium-Based Catalytic Systems

Zhu

Wang

2011

Designed Monomers and Polymers

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“…It could be seen that the productivities were in the order of , polydispersity of 2.77, and melting points of 106 and 123 8C with the same tandem system but at lower temperature (90 8C) and higher pressure (45 bar). [15] Compared to these literature data, we obtained high productivities but lower polymer molecular weights at higher temperature (110 8C vs. 90 8C) and lower pressure (31 bar vs. 45 bar). The heat of fusion of completely crystalline PE is 290 J g À1 .…”

Section: Tandem Polymerization At 110 8c and 31 Barcontrasting

confidence: 48%

“…Sasol Technology filed several patents and reported a method of combining bis(sulfanyl)amine or bis(phosphino) amine chromium complexes (SNS or PNP) as oligomerization catalyst with a metallocene catalyst for synthesis of polyethylene with butyl and/or hexyl branching. [12][13][14][15][16] Zhang et al [17][18][19] employed a trimerization SNS catalyst with rac-Et(Ind) 2 ZrCl 2 for ethylene polymerization at 49-74 8C. The products had T m 93.9-130.6 8C and X c 15.7-45.2%, respectively.…”

Section: Introductionmentioning

confidence: 99%

High Temperature High Pressure Tandem Polymerization of Ethylene for Synthesis of Ethylene‐1‐Hexene Copolymers from Single Reactor with SNS‐Cr and CGC‐Ti Catalysts

Guo

Fan

et al. 2014

Macro Reaction Engineering

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Ethylene-1-hexene copolymers are synthesized from ethylene using the tandem catalyst system of bis(2-dodecylsulfanyl-ethyl)amine-CrCl 3 (SNS-Cr) and [(h 5 -C 5 Me 4 )SiMe 2 ( t BuN)]TiCl 2 (CGC-Ti), with MAO as co-catalyst. The tandem polymerization is carried out in a hightemperature high-pressure solution process. SNS-Cr trimerizes ethylene and generates 1-hexene with high selectivity. CGC-Ti copolymerizes ethylene with 1-hexene and produces the ethylene-1-hexene copolymers. A short period of pre-trimerization is effective in increasing the 1-hexene content in copolymer and producing chains with uniform microstructure. The products prepared by this tandem system at high temperature and high pressure exhibit competitive mechanical properties with a commercial ethylene-1-octene copolymer.

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“…Compared to the conventional copolymerization approach, this tandem catalysis approach possesses an appealing advantage of using ethylene as the only monomer, which avoids the use of a-olefin and hence precludes the separate ethylene oligomerization process usually required in LLDPE production. [28,29] A number of versatile tandem catalysis systems, [28][29][30][31][32][33][34][35][36][37][38][39][40][41][42] particularly systems employing a combination of single-site homogeneous catalysts, have been successfully developed and summarized in recent review articles. [26,27] The concurrent tandem catalysis approach is conceptually elegant and virtually successful.…”

Section: Introductionmentioning

confidence: 99%

Long‐Chain Branching and Rheological Properties of Ethylene‐1‐Hexene Copolymers Synthesized from Ethylene Stock by Concurrent Tandem Catalysis

AlObaidi

Zhu

et al. 2005

Macro Chemistry & Physics

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Summary: Concurrent tandem catalysis systems have shown a significant advantage in the convenient synthesis of linear low‐density polyethylene (LLDPE) from a sole ethylene monomer stock by uniquely coupling the tandem action between an ethylene oligomerization catalyst and an ethylene copolymerization catalyst in a single reactor. Recently, we have reported the successful synthesis of ethylene‐hexene derived LLDPE using an effective concurrent tandem catalysis system comprising (η5‐C5H4CMe2C6H5)TiCl3 (1)/MMAO and a CGC copolymerization catalyst, [(η5‐C5Me4)SiMe2(tBuN)]TiCl2 (2)/MMAO. In this work, we report the results from an extensive study on the important rheological properties of LLDPE grades prepared with this tandem catalysis system. Two sets of LLDPE samples having different short‐chain branching density (SCBD) were prepared with the tandem catalysis system under various catalyst concentrations and at temperatures of 25 and 45 °C. The melt rheological properties of these polymers were evaluated using small‐amplitude dynamic oscillation measurements. These polymers have been found to possess typical rheological properties found in long‐chain branched (LCB) polymers, such as enhanced zero‐shear viscosity (η0), improved shear‐thinning, elevated dynamic moduli, and thermorheological complexity, which indicate the presence of long‐chain branching in the polymers. The long‐chain branching density (LCBD) of the two respective sets of polymers were qualitatively compared and correlated to the polymerization conditions including catalyst ratio and temperature. This work represents the first study on the rheological properties of LLDPE synthesized with concurrent tandem catalysis, and it discloses another appealing feature of this unique approach—its ability to produce LCB LLDPE from a single ethylene monomer stock.Synthesis of linear low‐density polyethylene (LLDPE) from ethylene using ethylene oligomerization catalyst and an ethylene copolymerization catalyst.magnified imageSynthesis of linear low‐density polyethylene (LLDPE) from ethylene using ethylene oligomerization catalyst and an ethylene copolymerization catalyst.

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Homogeneous Tandem Catalysis of Bis(2-decylthioethyl)amine−Chromium Trimerization Catalyst in Combination with Metallocene Catalysts

Cited by 38 publications

References 11 publications

Recent Research Progress in Preparation of Ethylene Oligomers with Chromium-Based Catalytic Systems

Recent Research Progress in Preparation of Ethylene Oligomers with Chromium-Based Catalytic Systems

High Temperature High Pressure Tandem Polymerization of Ethylene for Synthesis of Ethylene‐1‐Hexene Copolymers from Single Reactor with SNS‐Cr and CGC‐Ti Catalysts

Long‐Chain Branching and Rheological Properties of Ethylene‐1‐Hexene Copolymers Synthesized from Ethylene Stock by Concurrent Tandem Catalysis

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