Reactivation of a Poisoned Metallocene Catalyst by Irradiation with Visible Light

“Bound but Not Gagged”Immobilizing Single-Site α-Olefin Polymerization Catalysts

“…One of the most fascinating results to arise from the use of video microscopy is the effect that illumination has on polymerization activity. − Kallio and co-workers set out to perform kinetic studies on silica-supported metallocene/MAO catalyst in the gas-phase polymerization of ethylene, using video microscopy. However, the group found that the illumination light caused reproducibility problems in their kinetic measurements.…”

“…The phenomena became more pronounced when the polymerization systems were treated with small amounts of dioxygen or carbon dioxide. The activity of the poisoned system reduced rapidly but totally recovered after approximately 20 min of irradiation . Such experiments led the group to postulate that irradiation dissociates dioxygen or carbon dioxide from the metal center while having little to no effect on the coordination of ethylene.…”

Effect of Light Exposure on UV‐Vis Spectrum of [(nBuCp)2ZrCl2] Based Catalyst

“…The observations are similar to those in ethylene polymerisation studies where the highest activation effect of light was reported for the systems with added oxygen -light irradiation increased activity more in these cases. [10] Conclusions UV-vis spectroscopy can be successfully applied in metallocene catalyst studies since the metallocene catalyst species absorb at this wavelength range. UV-vis spectroscopic study on a [(nBuCp) 2 ZrCl 2 ]/MAO/VCH catalytic system showed that light irradiation favours the VCH interaction with the catalyst.…”

“…O 2 was added when required as dried air into the cells, as done in the earlier reported polymerisation experiments. [10] The UV-vis spectra were scanned using a Perkin Elmer Lambda 900 spectrophotometer. For supported catalysts an integrating sphere diffuse reflectance accessory was used to enable the measurement in reflectance mode.…”

“…Catalyst activity was totally recovered when an O 2 treated polymerisation system was exposed to light. [10] In the present study the reasons for the above-described phenomena caused by light irradiation and oxygen treatment on a zirconocene-MAO-vinylcyclohexane catalytic system were studied using UV-vis spectroscopy.…”