Reaction kinetics study of ethylene oligomerization into linear olefins over carbon-supported cobalt catalysts

Abstract

Ethylene oligomerization over carbon-supported cobalt catalysts at 200 °C selectively produces linear olefins (>80% linearity up to C12 olefins at < 48% conversion) and linear alpha olefins (LAOs) (>30% LAO isomer distribution up to C8 olefins at < 10% conversion). Increasing the catalyst pretreatment temperature from 230 to 560 °C in argon prior to a reaction reduces cobalt oxide to cobalt metal and increases the catalytic activity. Cobalt metal supported on carbon deactivates during the reaction, likely due to higher rate of polyethylene formation which decreases the catalytic activity. The product distribution follows a Schulz-Flory distribution. The reaction is first order with respect to ethylene partial pressure, suggesting a mechanism where ethylene reacts with adsorbed olefins on a surface that is highly covered with olefins.