Trimerization of ethylene catalyzed by Cr-based catalyst immobilized on the supported ionic liquid phase

Two types of heterogeneous catalysts based on bis(2-dodecylsulfanyl-ethyl)-amine. CrCl3 complex immobilized into the modified SBA-15 channels has been synthesized. For the first catalyst [Cr-SNS@SBA-15(700)], the pristine mesoporous silica was subjected to dehydroxylation at 700 degrees C while another catalyst [Cr-SNS-IL(BF4)@SBA-15] was prepared using supported ionic liquid phase (SILP) with tetrafluouroborate (BF4) as a counter ion. The materials were characterized by transmission electron microscopy (TEM), nitrogen adsorption-desorption analysis, thermal gravimetric analysis (TGA), Fourier transform infrared (FTIR) spectroscopy, elemental analysis (CHNS), X-ray diffraction (XRD) and UV-Visible spectroscopy. The catalytic activity of both catalysts was then investigated for ethylene trimerization reaction under various reaction conditions by emphasizing the use of low catalyst loading and Al:Cr molar ratio. The studies indicated that Cr-SNS-IL(BF4)@SBA-15 catalyst showed higher activity than either Cr-SNS@SBA-15(700) or homogeneous Cr-SNS under exactly the same reaction conditions. It was found that supported BF4- ions play a crucial role in the improvement of catalytic activity and selectivity to 51079 and > 99%, respectively. This study would open a new window in the design of types of supported catalysts for ethylene oligomerization mediated by more appropriate catalytic activity and selectivity. (C) 2017 Elsevier B.V. All rights reserved.