Results 171 to 180 of about 2,112 (213)

Selectivity in Propene Polymerization with Metallocene Catalysts

Chemical Reviews, 2000
Luigi Resconi, Luigi Cavallo, Anna Fait   +2 more
exaly   +4 more sources

Supported Metallocene Catalysts

CATTECH, 2000
Single-site olefin polymerization catalysts have been researched extensively and are now achieving wide acceptance in the polyolefin industry. To achieve commercial significance in the majority of today's commercial processes, these soluble catalysts must be immobilized on a carrier.
Edmund M. Carnahan, Grant B. Jacobsen
openaire   +1 more source

“Oscillating” Metallocene Catalysts:  What Stops the Oscillation?

Journal of the American Chemical Society, 2003
The 150 MHz (13)C NMR microstructural analysis of polypropylene samples produced with two representative "oscillating" metallocene catalysts of largely different steric hindrance, namely [(2-(3,5-di-tert-butyl-4-methoxyphenyl)indenyl)(2)ZrP](+) and [(2-phenylindenyl)(2)ZrP](+) (P = polymeryl), and the implications on the origin of the stereocontrol are
BUSICO, VINCENZO, Van Axel Castelli Valeria, Aprea Paola, CIPULLO, ROBERTA, Segre Annalaura, TALARICO, GIOVANNI, VACATELLO, MICHELE   +6 more
openaire   +7 more sources

Hard versus Soft Materials as Supports for Metallocene and Post‐Metallocene Catalysts

Macromolecular Reaction Engineering, 2009
AbstractThe influence of organic supports on the polymerization behavior of post‐metallocene catalysts is studied and compared with similarly supported titanium and zirconium metallocenes. The effects of the immobilization, activation, and polymerization process were studied by video microscopy, laser confocal fluorescence microscopy, SEM, and TEM.
Naundorf, C., Ferrari, D., Rojas, G., Fink, G., Klapper, M., Müllen, K.   +5 more
openaire   +3 more sources

Metallocene and Ziegler-Natta Catalysts

2021
Fifty years ago, Karl Ziegler and Natta won the Nobel Prize for their discovery of the catalytic polymerization of ethylene and propylene using titanium compounds with aluminum-alkyls as co-catalysts. Polyolefins are constantly growing and are now one of the most important highconsumption polymers. New metallocene/methylaluminoxane (MAO) catalysts have
Vinod Vishwakarma, Sandeep, Kulkarni, S.G.   +1 more
openaire   +1 more source

Heterogeneous Metallocene Catalysts

1995
Copolymerizations of olefins were carried out with the SiO2-, AI2O3- and MgCl2-supported Et[IndH4]2ZrCl2 catalysts combined with AIR3 as cocatalyst and the results were compared with those obtained previously in the presence of homogeneous Et[IndH4]2ZrCl2-MAO catalyst.
Kazuo Soga, Manabu Kaminaka, Hyun Joon Kim, Takeshi Shiono   +3 more
openaire   +1 more source

Inversion of stereoselectivity in a metallocene catalyst

Macromolecular Rapid Communications, 1996
AbstractInversion of stereoselectivity of a particular metallocene (Me2Si(Flu) (N‐t‐Bu)ZrCl2) (Me: methyl, Flu: fluorenyl, t‐Bu: tert‐butyl) from syndiospecific into isospecific was observed by changing the cocatalyst from methylaluminoxane (MAO) to [Ph3C]+ [B(C6F5)4]−/AliBu3 (iBu:isobutyl).
Tetsunosuke Shiomura, Tadashi Asanuma, Norihide Inoue   +2 more
openaire   +1 more source

Heterogenization of Metallocene Catalysts for Alkene Polymerization

Angewandte Chemie International Edition, 1999
Beyond mere convenience: In large-scale industrial processes for alkene polymerization the essentially homogeneous metallocene/activator catalyst systems are heterogenized (example shown) to improve polymer properties. New mesoporous and organic catalyst supports and their application in this field of catalysis are described.
openaire   +3 more sources

Olefin copolymerization with metallocene catalysts. III. Supported metallocene/methylaluminoxane catalyst for olefin copolymerization

Journal of Polymer Science Part A: Polymer Chemistry, 1991
AbstractSupported catalyst for fluidized bed polymerization processes has been prepared by reacting macroporous SiO2 first with MAO (methylaluminoxane) and then with Et [Ind]2ZrCl2. It contains 0.60 wt % of Zr and an [Al]/[Zr] ratio of 50. This catalyst produces homogeneous E/P (ethylene/propylene) copolymers with truly random copolymerization ...
James C. W. Chien, Dawei He
openaire   +1 more source

Alternating Ethene/Propene Copolymerization with a Metallocene Catalyst

Angewandte Chemie International Edition, 1998
A small variation in the substituent R' on the metallocene catalyst employed in the copolymerization of ethene and propene leads to a highly alternating (81-83%) structure (1) rather than a statistical copolymer. Such copolymers were until recently only accessible by hydrogenation of polyisoprene or 1,4-poly(pentadiene).
Margarete K, Leclerc, Robert M, Waymouth
openaire   +2 more sources