ORGANOMETALLIC VANADIUM-BASED HETEROGENEOUS CATALYSTS FOR ETHYLENE POLYMERIZATION - STUDY OF THE DEACTIVATION PROCESS

Slurry polymerizations of ethylene over vanadium catalysts (based on V Cl4 and VOCl3) and their MgCl2(THF)(2)-supported equivalents were stud ied. Unsupported vanadium catalysts were found to be unstable while th e vanadium active sites deposited on the MgCl2(THF)(2) complex are sta ble. A sharply outlined correlation was found between the concentratio n of vanadium(LU) and catalyst productivity. The high activity and sta bility of the vanadium catalyst when supported on the magnesium comple x is attributed to the increase of resistance to reduction of active v anadium(III) to inactive vanadium(II) by an organoaluminium co-catalys t.