Transition Metal Single Site Catalysts – From Homogeneous to Immobilized Systems

Recent Developments in the Chemistry of Cubic Polyhedral Oligosilsesquioxanes

“…It should also be noted that the use of incompletely condensed silsesquioxanes such as T 7 R 7 (OH) 3 and related metallasiloxanes as mimics for silica surfaces and catalyst supports has also been reviewed. – …”

Titanium and Zirconium Permethylpentalene Complexes, Pn*MCpRX, as Ethylene Polymerization Catalysts

“…Well-defined homogeneous group 4 complexes are of interest as alternatives to Ziegler–Natta or Phillips-type polymerization systems, owing to the improved control over polymer properties . Alternatively, the use of surface organometallic chemistry to immobilize these well-defined complexes on solid supports targets the preparation of single-site heterogeneous catalysts and is known to limit reactor fouling while retaining desirable polymer properties. , The O’Hare group has been exploring this methodology to prepare ethylene polymerization catalysts and to study both structure–activity relationships and the nature of the active species on the surface …”

Insights into carbon nanotube growth using an automated gravimetric apparatus

“…Even these best estimates are inaccurate because not all Fe particles necessarily result in CNT growth [91]. The comparatively low yield obtained from the silica support requires further study but it likely stems from a combination of (i) Fe agglomeration -mean Fe crystallite size estimated from XRD by the Scherrer equation (0.9 shape factor) increased from $20 nm in Fe 2 O 3 to $30 nm in Fe; (ii) differences in substrate acid-base properties [92]; and (iii) the formation of surface Fe-silanol complexes that further reduce catalytic availability and/or performance [93].…”