Unravelling the Role of Al-alkyl Cocatalyst for the VOx/SiO2 Ethylene Polymerization Catalyst: Diethylaluminum Chloride Vs.Triethylaluminum...

摘要

Vanadium-based compounds are one of the most important classes of catalysts for olefin coordination polymerization.When used in combination with Al-alkyl cocatalysts,they yield high molecular weight polyolefins.However,in comparison to their titanium-based counterparts,vanadium-based Ziegler-Natta catalysts are severely limited due to their fast deactivation-generally believed to originate from the thermodynamic instability of the V active species.Herein,the authors report the results of theoretical studies on VOx/SiO2/diethylaluminum chloride(DEAC) and VOx/SiO2/triethylaluminum(TEA) with V(lll) and V(IV) cluster models(Figure 1).Their results provide a comprehensive insight into how this catalyst system is affected by cocatalysts and why DEAC and TEA differ in their activation of the vanadium-based catalyst.