Ethylene oligomerization into linear olefins over cobalt oxide on carbon catalyst

Here, we show that C-4-C-12 linear olefins, including linear alpha olefins, can be selectively produced from ethylene over a stable cobalt oxide on carbon catalyst. Both bulk and surface cobalt phases are CoO when the catalyst is stable, suggesting CoO is the stable cobalt phase for oligomerization. During the reaction, polyethylene forms in the catalyst pores which influences the product selectivity. The catalyst is more stable at higher temperatures (similar to 200 degrees C) likely due to reduction of Co3O4 to CoO while rapid deactivation is observed at lower temperatures (e.g., 80-140 degrees C). The product selectivity can be fit to two different Schulz Flory distributions, one from C-4 to C-10 olefins and one above C-10 olefins, suggesting that transport restrictions influence product selectivity. At 48.3% conversion, product linearities up to C-12 olefins are above 90%, making it the most selective heterogeneous catalyst to linear olefins to date in the absence of activators and/or solvents.

Automated summary

A stable cobalt oxide on carbon catalyst can selectively produce C-4-C-12 linear olefins, including linear alpha olefins, from ethylene. The product selectivity is influenced by the formation of polyethylene in the catalyst pores. The catalyst exhibits higher stability at higher temperatures and rapid deactivation at lower temperatures, likely due to reduction of Co3O4 to CoO.