Oligomerization of Ethylene to Produce Linear α-Olefins Using Heterogeneous Catalyst Prepared by Immobilization of α-Diiminenickel(II) Complex into Fluorotetrasilicic Mica Interlayer

Author： Kurokawa Hideki Miura Kazuki Yamamoto Kazuhiro Sakuragi Tsutomu Sugiyama Takao Ohshima Masa-aki Miura Hiroshi

Publisher： MDPI

E-ISSN： 2073-4344|3|1|125-136

ISSN： 2073-4344

Source： Catalysts, Vol.3, Iss.1, 2013-02, pp. : 125-136

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Abstract

Heterogeneous catalysts for production of linear α-olefins from ethylene were prepared by the direct reaction of the α-diimine ligand [L: R-N=C(R')-C(R')=N-R; R' = Me and R = 2,6-Me₂Ph (L5), 2,5-Me₂Ph (L1), 2-MePh (L2), or Ph (L3); R' = 1,8-naphth-diyl and R = Ph (L4)] and Ni²⁺ ion-exchanged fluorotetrasilicic mica. Only high molecular weight polyethylene was obtained in the reaction using the L5/Ni²⁺-Mica procatalyst activated by AlEt₃ (TEA) as an activator, whereas the TEA-activated L1- and L2/Ni²⁺-Mica procatalysts afforded a mixture of a large amount of low-molecular weight polyethylene and a small amount of oligomers having 4-22 carbons. The procatalyst consisting of Ni²⁺-Mica and the L3 ligand that possesses non-substituted phenyl groups on the iminonitrogen atoms effectively promoted the oligomerization of ethylene after its activation with TEA, resulting in the fact that the ethylene oligomers were produced with a moderate catalytic activity (101 g-ethylene g-cat⁻¹ h⁻¹ at 0.7 MPa-ethylene) in the presence of TEA. When the backbone was varied from the butane moiety (L3) to acenaphthene (L4), the solid product dramatically increased. The weight percentage of the oligomers in the total products increased with the increasing reaction temperature; however, an insignificant increase in the oligomers was observed when the ethylene pressure was decreased.