Structure Evolution of Co-CoOx Interface for Higher Alcohol Synthesis from Syngas over Co/CeO2 Catalysts

CeO2 nanorods supported Co-CoOx catalysts showed high selectivity for higher alcohol synthesis (HAS) from syngas. The selectivity has found to increase with lowering the Co loadings, and the value over Co-1/CeO2 (19.86%) is twice higher than that over Co-5/CeO2 (8.67%). The active sites at the interfaces between Co-0 and CoOx, or to say, Co-Co-x pairs, have evidenced to be responsible for HAS. The strong metal-support interactions between Co and CeO2 retard the reduction of CoOx and stabilize the intermediates such as CO-Co delta+. Likely, CO favors dissociating on the metallic Co surface to form CHx species, while CO is associatively activated on Co delta+ sites. Moreover, the structure evolution of the Co-CoOx interface was revealed during calcination, reduction, and reaction using in situ X-ray diffraction (XRD), in situ Raman spectroscopy, X-ray absorption spectroscopy (XAS), and in situ diffuse reflectance infrared fourier transform spectroscopy (CO-DRIFTS). The structure-performance relationship of HAS over Co/CeO2 was proposed.