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Synthesis and characterization of amine-functionalized supported phosphine catalysts and their application in ethylene oligomerization


Mzamo L. Shozi
Xolelwa Zulu
Holger B. Friedrich

Abstract

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 of 45–100 °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.


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eISSN: 1996-840X
print ISSN: 0379-4350