Biphasic trimerization of ethylene with diphosphinoamine/chromium(III)/methylaluminoxane immobilized in organochloroaluminate ionic liquid

PNP/Cr(III)/MAO was proved to be an effective catalyst system for the tetramerization of ethylene toward 1-octene with high catalytic activity and high selectivity. In 1- n -butyl-3-methylimidazolium organoaluminate ionic liquid/cyclohexane biphasic systems, PNP/Cr(III)/MAO showed an impressive selectivity switch from ethylene tetramerization to ethylene trimerization. The influence of ionic liquid/Cr molar ratio, reaction temperature, reaction pressure and recycling runs on performance of the catalytic system were investigated in detail. These data suggest that the organoaluminate anion associates with the active chromium species, giving rise to more active and selective Cr-systems for trimerization of ethylene to 1-hexene.