A novel non-metallocene titanium complex was synthesized, and used as the catalyst for ethylene polymerization. It results in an acceptable activity, affording the polyethylene with ultra high molecular weights, and relative broad molecular weight distributions. Moreover, the molecular weight almost doesn’t change with the change of Al/Ti ratio.

Understanding the kinetics of olefin polymerization with Ziegler-Natta and related catalysts means identifying the main kinetic parameters such as k(p) and concentration of active sites. The high-pressure quenched-flow technique could be an absolute method for counting active sites and for activation studies of molecular catalysts. A kinetic study of metallocene catalysts and a phenoxy-imine ti...

We treated silica with tris(pentafluorophenyl)borane, B(C6F5)3, to create borane-functionalized support, SiO2–B(C6F5)3 which was then used as a support and co-catalyst for the in situ activated dichloro-zirconocene (Cp2ZrCl2/TIBA) and dimethyl-zirconocene catalyst systems (Cp2Zr(CH3)2) for ethylene polymerization. The surface modifications of SiO2– B(C6F5)3 was investigated by SEM–EDX, FTIR and...

We report a numerical investigation on the catalytic growth mechanism of a single-walled carbon nanotube (SWNT) inside a template SWNT, that is, formation of a double-walled carbon nanotube (DWNT). The molecular dynamics simulations together with complementary ab inito calculations suggest that the DWNT formation from thermally annealed metallocene-encapsulating SWNT goes through formation of m...

A series of dinitrogen-bridged dimolybdenum-dinitrogen complexes bearing metallocene-substituted PNP-pincer ligands is synthesized by the reduction of the corresponding monomeric molybdenum-trichloride complexes under 1 atm of molecular dinitrogen. Introduction of ferrocene as a redox-active moiety to the pyridine ring of the PNP-pincer ligand increases the catalytic activity for the formation ...

Both metallocene and Phillips chromium catalysts are used in the commercial manufacture of polyethylene. Unlike most other systems, Chevron Chemical (CPC) platform does not use methylaluminoxane or fluoroorganic boranes. Instead, support itself serves to activate (ionize) metallocenes, which then polymerize ethylene at high activity. Most these solid acid supports can also be anchor Cr make a c...

A variety of group 4 metal catalytic systems (C2-symmetric {EBTHI}-, {SBI}-type zirconocene complexes (C2-1–4); C1-symmetric (C1-5–8) and Cs-symmetric (Cs-9) {Cp/Flu}-type zirconocene complexes; Cp*2ZrCl2 (Cp* 2-10)), half-metallocene complexes (CpTiCl3, HM-11), constrained-geometry (CGC-12) titanium catalysts) and post-metallocene catalysts (Dow’s ortho-metallated amido-pyridino hafnium comple...

Copolymerization of ethylene with 1-hexene was carried out using two ansa-fluorenyl titanium derivative complexes. The substituent effect on the catalytic activity, monomer reactivity ratio and polymer property was investigated. It was found that the presence of t-Bu groups on fluorenyl ring exhibited remarkable catalytic activity and produced polymer with high molecular weight. However, these ...

Albert J. van Reenen and Omar Sultan Department of Chemistry and Polymer Science, University of Stellenbosch, Private Bag X1, Matieland 7602, South Africa Reprint requests to Dr. A. J. van Reenen. Fax: +27-21-8084967. E-mail: [email protected] Z. Naturforsch. 2007, 62b, 362 – 366; received November 1, 2006 Dedicated to Prof. Helgard G. Raubenheimer on the occasion of his 65th birthday TwoC2-symmet...