Untitled

Chien, James C. W.

doi:10.1023/a:1019111700284

Cited by 117 publications

(61 citation statements)

References 82 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…3) [13][14][15]. This highly active homogeneous system allows for tuning of the product polymer microstructure (M w , PDI, % comonomer incorporation, tacticity) exclusively by varying the organic ancillary ligands surrounding the group 4 metal [14,[16][17][18][19][20][21][22][23][24].…”

Section: Introductionmentioning

confidence: 99%

Supported Single-Site Organometallic Catalysts for the Synthesis of High-Performance Polyolefins

2014

View full text Add to dashboard Cite

Single-site organometallic catalysts supported on solid inorganic or organic substrates are making an important contribution to heterogeneous catalysis. Early and late transition metal single-site catalysts have changed the polyolefin manufacturing industry and research with their ability to produce polymers with unique properties. Moreover, several of these catalysts have been commercialized on a large scale. Their heterogenization for slurry or gas phase olefin polymerization is important to produce polyolefin as beads and to avoid reactor fouling. The large majority of supports currently used in industry are inorganic materials (SiO 2 , Al 2 O 3 , MgCl 2 ), with silica being the most important. Single-site supported catalysts are most commonly prepared by molecular-level anchoring/chemisorption, in which a molecular precursor undergoes reaction with the surface while maintaining most of the ligand sphere of the parent molecule. Chemisorption of discrete organometallic complexes on solid supports yields catalysts with well-defined active sites, greater thermal stability than the homogeneous analogues, and decreased reactor fouling versus the homogeneous analogues. This review presents a detailed account of the synthesis, characterization and polymerization properties of single-site catalysts supported on metal oxides and metal sulfated oxides, primarily carried out at Northwestern University.

show abstract

Section: Introductionmentioning

confidence: 99%

Supported Single-Site Organometallic Catalysts for the Synthesis of High-Performance Polyolefins

2014

View full text Add to dashboard Cite

show abstract

“…Unfortunately, the metallocene systems, both homogeneous and heterogeneous, have disadvantageous features hindering their application in industrial scale processes [6][7][8]. Therefore, there is a need to search for new methods of the olefin polymerization using the metallocene catalysts, but deprived of toxic solvents (toluene, xylene), great excess of activator methylaluminoxane (MAO) [9] and multi-step anchorage of the metallocene on a solid support [6][7][8][9]. An innovative method for the olefin polymerization can be liquid-liquid biphasic system.…”

Section: Introductionmentioning

confidence: 99%

Effect of immobilization of titanocene catalyst in aralkyl imidazolium chloroaluminate media on performance of biphasic ethylene polymerization and polyethylene properties

2012

View full text Add to dashboard Cite

], were applied as media of the Cp 2 TiCl 2 catalyst for biphasic ethylene polymerization. The studied aralkyl ionic liquids ensure greater stability of the catalyst at higher temperatures and more regular morphology of the produced polyethylene than analogous 1-n-alkyl-3-methylimidazolium chloroaluminates. The alkylaluminium compound participates in the termination reaction of the polymer chain. The catalyst is stable and enables recycling of the ionic liquid phase in the consecutive polymerization reactions. The [Ph-C 2 mim][AlCl 4 ] ionic liquid and AlEt 2 Cl alkylaluminium compound turned out to be the most suitable for the biphasic process. The influence of the kind of ionic liquid, alkylaluminium compound (AlEt 2 Cl and AlEtCl 2 ), activator/catalyst molar ratio, reaction temperature, reaction time and catalyst recycling on the polymerization performance as well as polyethylene properties such as molecular weight (M w ), polydispersity, melting temperature, crystallinity degree, bulk density and particle size is presented.

show abstract

“…The effectiveness of perfluoroarylboranes and borates as activators for metallocene and related metal alkyls is well established and has recently been reviewed by Chen and Marks. 16 Zirconocene dialkyls are typically activated using [Ph 3 18 Borate activators can also be used in combination with metallocene dichlorides, if a third component such as triisobutylaluminum able to alkylate the metallocene is present. 19,20 Tethering of a borate activator to magnesium chloride, involving activators containing a Lewis base functionality able to coordinate to the Lewis acidic support, has recently been described.…”

Section: Introductionmentioning

confidence: 99%

“…19,20 Tethering of a borate activator to magnesium chloride, involving activators containing a Lewis base functionality able to coordinate to the Lewis acidic support, has recently been described. 21 3 , with the aim of tethering the borate to the support material via reaction of a Si-O-Al-R moiety with the active hydrogen of the borate. 22 The use of analogous trialkylammonium borates having long hydrocarbyl chains on the ammonium cation and having improved solubility in toluene has also been described.…”

Section: Introductionmentioning

confidence: 99%

Metallocene‐catalyzed olefin polymerization using magnesium chloride‐supported borate activators

Smit

Severn

Zheng

et al. 2005

J of Applied Polymer Sci

View full text Add to dashboard Cite

New approaches have been identified for the immobilization, on a MgCl 2 -based support, of borate activators for metallocene-catalyzed olefin polymerization. Immobilization of [HNEt 3 ][B(C 6 F 5 ) 3 (C 6 H 4 -4-OH)] was carried out by reaction with a support of type MgCl 2 /AlR n (OEt) 3Ϫn , obtained by reaction of AlEt 3 with an adduct of magnesium chloride and ethanol. Use of the resulting immobilized borate in combination with zirconocene catalysts in ethylene and propylene polymerization resulted in significantly higher polymerization activities than were obtained using the same borate immobilized on a silica support. The MgCl 2 -based support also gave the better polymer particle morphology, cross-sectional imaging indicating uniform support fragmentation, as opposed to incomplete fragmentation using the silica support. High catalyst activities were obtained using a MgCl 2 /AlR n (OEt) 3Ϫn support impregnated with [Ph 3 C][B(C 6 F 5 ) 4 ]. In this case, a highly porous polyethylene particle morphology was obtained.

show abstract

Untitled

Cited by 117 publications

References 82 publications

Supported Single-Site Organometallic Catalysts for the Synthesis of High-Performance Polyolefins

Supported Single-Site Organometallic Catalysts for the Synthesis of High-Performance Polyolefins

Effect of immobilization of titanocene catalyst in aralkyl imidazolium chloroaluminate media on performance of biphasic ethylene polymerization and polyethylene properties

Metallocene‐catalyzed olefin polymerization using magnesium chloride‐supported borate activators

Contact Info

Product

Resources

About