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

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 degrees 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.

Automated summary

A series of phosphorus and nitrogen-based ethylene oligomerization ligands were reported, characterized, and tested for activity and selectivity towards 1-octene. The supported catalysts showed comparable activity to their homogeneous counterparts, with high selectivities to 1-octene in the C8 products.