Cobalt-Ceria Catalysts for the Methanol Decomposition: Insights in the Long-Term Stability and Methanol Interaction

Cobalt-ceria catalysts (5 wt% in Co) were prepared using two different approaches: (i) a one-step synthesis through the EDTA-citrate complexing method, and (ii) via a traditional wet impregnation method. Materials were characterized by XRD, Raman, N 2 -adsorption, EDS, SEM, TEM, XPS, H 2 -TPR and O 2 -TPO. The catalytic properties in the methanol decomposition (MD) reaction were studied in a conventional flow reactor coupled to a GC, while in-situ DRIFTS studies followed the methanol surface reactivity. Moreover, DFT calculations on the methanol interaction with the Co/CeO 2 system were performed to elucidate the mechanisms behind the MD. Catalytic tests showed that both cobalt-ceria catalysts exhibited excellent stability and significantly high hydrogen yields regardless of the synthesis procedure. Besides, during long-term operations (68 h on-stream), the impregnated sample (Co/CeO 2 -WI) exhibited an enhanced performance, attributed to the close interaction of cobalt species over the surface of the ceria support. In this regard, the DFT results showed that the Co dispersion on the ceria surface plays a dominant role in forming the methoxy group, exhibiting an evident selectivity to achieve the reaction. The DRIFTS study revealed an increased population of adsorbed carbonate species over the surface of the on-step catalyst (Co/CeO 2 -OS), probably blocking the active sites during long-term operations.