Ethylene tri-/tetramerization catalysts supported by diphosphinoindole ligands

Selective ethylene tetramerization: an overview

“…27). 182 These PNCP-type catalysts had reactivities and selectivities for ethylene oligomerization close to those of PCCP-type catalysts. Both smaller (248) and larger (252) site resistances led to decreased catalytic activity.…”

“…Therefore, multinuclear ligands are worthy of further exploration for industrialization. (180)(181)(182)(183). 85 Minor changes in the structure and reaction conditions led to the tetramerization of ethylene, rather than its trimerization.…”

Chromium-Based Complexes Bearing Aminophosphine and Phosphine–Imine–Pyrryl Ligands for Selective Ethylene Tri/Tetramerization

“…The first selective ethylene tri/tetramerization system with Cr-based catalysts containing bis­(diphenylphosphino)-amine (PNP), bis­(diphenylphosphino) hydrazine (PNNP), or 1,2-bis­(diphenylphosphino)­ethane (dppe) ligand was discovered by Sasol in 2004. , A selectivity of 68.3% for 1-octene was obtained at 45 bar and 45 °C, along with the remaining products, which include 1-hexene, C 6 impurities, oligomers with higher carbon number, and polyethylene. Subsequently, in order to further improve the ethylene tri/tetramerization performance, typical PCCP, − PCN, PC 2 NCN, PCNP, PCSiNP, PNCN, , PNCNP, and PNPN , backbone ligands have been studied. Results show that multidentate ligands containing P and N donors have great potential to catalyze the selective ethylene oligomerization, yielding 1-hexene and 1-octene with high selectivities. , In a previous work, Yang and co-workers introduced the pyridine–phosphine (PNCN) ligand variations by modifying the phosphine substituents, which affected the ligand bite angles and flexibility .…”

“… 13 , 14 A selectivity of 68.3% for 1-octene was obtained at 45 bar and 45 °C, along with the remaining products, which include 1-hexene, C 6 impurities, oligomers with higher carbon number, and polyethylene. Subsequently, in order to further improve the ethylene tri/tetramerization performance, typical PCCP, 15 − 20 PCN, 21 PC 2 NCN, 22 PCNP, 23 PCSiNP, 24 PNCN, 25 , 26 PNCNP, 27 and PNPN 28 , 29 backbone ligands have been studied. Results show that multidentate ligands containing P and N donors have great potential to catalyze the selective ethylene oligomerization, yielding 1-hexene and 1-octene with high selectivities.…”

Chromium Ethylene Tri-/Tetramerization Catalysts Supported by Iminophosphine Ligands

“…The past two decades have seen an increasing demand for linear α-olefins (LAOs) mainly due to the extensive use of 1-hexene and 1-octene as comonomers with ethylene for the production of linear low-density polyethylene (LLDPE). − Generally, LAOs are produced with a broad range of olefins from C 4 to C 20 based on the Schulz–Flory distributions manufactured by Shell, Ineos, SABIC, and Chevron–Phillips . In order to meet market demand growth by avoiding the production of less valuable or lower-volume LAOs, selective ethylene oligomerization catalysts are highly desirable and have been developed for use on an industrial scale. − Considerable success has been achieved by employing chromium-based catalysts in developing highly active ethylene trimerization systems for manufacturing 1-hexene, − including the Chevron–Phillips’ pyrrole, , the BP diphosphinoamine (PNP), and the Sasol mixed heteroatomic systems …”