Chromium-based selective ethylene tri-/tetramerization catalysts supported by two-carbon bridged diphosphine ligands

The effect of backbone-substituent of carbon-bridged diphosphine ligands of the type {Ph2PC(COOR)=C(COOR)PPh2} on the catalyst performance in ethylene oligomerization has been explored. The Cr precatalyst supported by the ligand {Ph2PC(COOMe)=C(COOMe)PPh2} (L1) achieved a high activity of 1800 kg/g Cr/h with a total selectivity of 90.8% toward 1-hexene (77.3%) and 1-octene (13.5%) when activated with MMAO-3A. The catalytic system based on these ligands exhibited considerably high thermal stability, maintaining high activity even at 100 oC.