Anchoring via covalent binding of β-diimine-nickel complexes in SBA-15 and its application in catalytic reactions

Abstract

The β-diimine ligands 2-(phenyl)amine-4-(phenyl)imine-2-pentene (L1) and 2-(2,6-dimethylphenyl)amine-4-(2,6-dimethylphenyl)imine-2-pentene (L2) were anchored covalently to SBA-15. The ligands were combined with (3-chloropropyl) trimethoxysilane (CPTMS), which is a trialkoxysilane group, and anchored to a mesoporous SBA-15 support through a complexation of the silanols of the silica matrix with nickel. These complexes were synthesized as catalysts precursors for ethylene and propylene oligomerization processes. The support was first synthesized and calcined before being anchored to the ligand, generating the nickel complex. These materials were characterized using various techniques such as 13C and 29Si NMR, small angle XRD, thermogravimetric analysis, N2 adsorption, transmission electron microscopy, elemental analysis and flame atomic absorption spectroscopy. The heterogenized complexes are active and selective during ethylene and propylene oligomerization, generating C4 and C6 products and alkylation products ranging from C10–C16. The alkylation process being a parallel reaction. The Ni-β-diimine/SBA-15 (SC1) complexes showed an activity of 7.2×103h−1 for the ethylene oligomerization with 98% selectivity toward α- and C4 products and an activity of 2×103h−1for the propylene oligomerization with a 13% selectivity toward C6 linear products. The results of the oligomerization reactions reveal the influence of the support on the products obtained.