Performance of various aluminoxane activators in ethylene tetramerization based on PNP/Cr(III) catalyst system

Ethylene tetramerization with PNP/Cr(III)/aluminoxanes was investigated. By comparing catalytic activity, selectivity to 1-octene and selectivity to methylenecyclopentane in ethylene tetramers, the effects of various aluminoxanes on ethylene tetramerization were discussed. The results showed that MMAO(TMA-depleted), MAO and EAO were all effective cocatalyst for ethylene tetramerization toward 1-octene. PNP/Cr(III)/MMAO catalytic systems afford the highest catalytic activity and the highest selectivity to 1-octene. The selectivities to methylenecyclopentane was decreased by using i-BAO and EAO as cocatalyst, which indicated that different mechanism for ethylene tetramerization has been occurred in such cases.