Ethanol dehydrogenation to acetaldehyde over Co@N-doped carbon

Abstract

Cobalt and nitrogen co-doped carbon materials (Co@CN) have recently attracted significant attention as highly efficient noble-metal-free catalysts exhibiting a large application range. In a similar research interest, and taking into account the ever-increasing importance of bioethanol as a renewable raw material, here, we report the results on ethanol dehydrogenation to acetaldehyde over Co@NC catalysts. The catalyst samples were synthesized by a variety of affordable techniques, ensuring generation of various types of Co species incorporated in carbon, such as subnanosized cobalt sites and nano-sized particles of metallic cobalt and cobalt oxides. The catalytic activity was tested under both oxidative and non-oxidative gas-phase conditions at 200–450 °C using a fixed-bed flow reactor. The non-oxidative conditions proved to be much more preferable for the target reaction, competing, however, with ethanol dehydration to ethylene. Under specified reaction conditions, ethanol conversion achieved a level of 66% with 84% selectivity to acetaldehyde at 400 °C. The presence of molecular oxygen in the feed led mainly to deep oxidation of ethanol to COx, giving acetaldehyde in a comparatively low yield. The potential contribution of carbon itself and supported cobalt forms to the observed reaction pathways is discussed.