Effect of support nature on the cobalt-catalyzed CO2 hydrogenation

- The CO2 methanation performance of cobalt-based catalysts is explored.
- The impact of support (CeO2, ZrO2, Gd2O3, ZnO) was investigated.
- Co/CeO2 catalyst exhibited an up to 100% conversion of CO2 to methane at 300 °C.
- The superiority of Co/CeO2 catalyst can be ascribed to its enhanced reducibility.
- Co/ZnO catalyst was progressively activated under reaction conditions.

CO2 hydrogenation to value added chemicals/fuels has gained considerable interest, in terms of sustainable energy and environmental mitigation. In this regard, the present work aims to investigate the CO2 methanation performance of cobalt-based catalysts supported on different metal oxides (MxOy: CeO2, ZrO2, Gd2O3, ZnO) at low temperatures (200-300 °C) and under atmospheric pressure. Various characterization methods, such as N2 adsorption-desorption at −196 °C, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and temperature-programmed reduction (TPR), were employed to correlate the structural and surface properties of the materials with their catalytic activity. The results revealed a significant impact of support nature on the CO2 hydrogenation performance. The following order, in terms of CH4 yield (YCH4), was recorded at 300 °C: Co/CeO2 (∼96%) > Co/ZnO (∼54%) > Co/G2O3 (∼53%) ∼ Co/ZrO2 (∼53%). On the basis of the characterization results, the superiority of Co/CeO2 catalyst can be mainly ascribed to its enhanced reducibility linked to Co-Ceria interactions. Moreover, Co/CeO2 demonstrated a stable conversion/selectivity performance under subsequent reaction cycles, in contrast to Co/ZnO, which progressively activated under reaction conditions. The latter is related with the modifications induced in elemental chemical states and surface composition of Co/ZnO upon pretreatment in reaction conditions, in contrast to Co/CeO2 sample where a stable surface performance was observed.

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