Kinetic and mechanistic insights into Ni-AlKIT-6 catalyzed ethylene oligomerization

Abstract

A kinetic study of the ethylene oligomerization on a mesoporous 2 wt% Ni-AlKIT-6 was performed in a fixed bed flow reactor. The temperature ranged from 40 to 120 °C, the inlet ethylene partial pressure from 0.1 to 2.0 MPa and the space velocity (WHSV) was between 37 and 240 h⁻¹. The main products identified at low ethylene conversion were n-butenes (90%) and hexenes (9%). A coordination–insertion mechanism (Cossee–Arlman) was proposed to explain the formation of these primary products. An activation energy of 15.2 kJ mol⁻¹ and a global kinetic order of 1.28 were determined. The experimental data suggest that the kinetically limiting step is the insertion of ethylene into the metal–alkyl bond.