Synthesis of a novel triple-site diphosphinoamine (PNP) ligand and its applications in ethylene tetramerization

A novel triple-site diphosphinoamine (PNP) ligand was synthesized and characterized. In combination with Cr(III) and methylaluminoxane (MAO), it generated active catalytic systems for ethylene tetramerization toward 1-octene with high catalytic activity and long lifetime. The effects of reaction temperature, molar ratio of Al/Cr and molar ratio of ligand/Cr on catalytic activity and selectivity to 1-octene were studied with reaction kinetics of the catalytic system for ethylene tetramerization described. At the Al/Cr molar ratio of 100, the catalytic activity is up to 2.29x106 g·mol−1 (Cr)·h−1 and the selectivity to 1-octene is 49.65 wt%.