Abstract

SHOZI, Mzamo L.; ZULU, Xolelwa  and  FRIEDRICH, Holger B.. Synthesis and characterization of amine-functionalized supported phosphine catalysts and their application in ethylene oligomerization. S.Afr.j.chem. (Online) [online]. 2022, vol.76, pp.9-13. ISSN 1996-840X.  https://doi.org/10.17159/0379-4350/2022/v76a02.

A series of phosphorus and nitrogen-based ethylene oligomerization ligands of the type Ph₂PN(X)PPh₂ where X = i-propyl, n-butyl, ethylbenzene and cyclohexyl substituents are reported. These ligands were functionalized to enable tethering on amino-silica. The free ligands, amino-silica and the tethered ligands were characterized by BET, XRD, IR, TGA and NMR. The catalysts were tested for ethylene oligomerization using Cr(acac)₃ (acac = acetylacetonate) as the precursor and MMAO (modified methylaluminoxane) as the activator. The activity and selectivity of these catalysts to 1-octene was monitored at 45 bar ethylene in the temperature range of45-100 °C. The activity of the supported catalysts was comparable to their homogeneous counterparts, surpassing them in some cases and selectivities to 1-octene in the C8 products were as high as 99 wt%. The steric effect of the substituent on the ligand as well as that of the support was found to influence the activity and product distribution.

Keywords : 1-hexene; 1-octene; ethylene oligomerization; phosphine ligands; silica; supported catalysts.

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