Effect of support nature on the cobalt-catalyzed CO2 hydrogenation

Abstract

CO 2 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 CO 2 methanation performance of cobalt-based catalysts supported on different metal oxides (M x O y : CeO 2 , ZrO 2 , Gd 2 O 3 , ZnO) at low temperatures (200-300 C) and under atmospheric pressure. Various characterization methods, such as N 2 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 CO 2 hydrogenation performance. The following order, in terms of CH 4 yield (Y CH4 ), was recorded at 300 C: Co/CeO 2 (96%) > Co/ZnO (54%) > Co/G 2 O 3 (53%) Co/ZrO 2 (53%). On the basis of the characterization results, the superiority of Co/CeO 2 catalyst can be mainly ascribed to its enhanced reducibility linked to Co-Ceria interactions. Moreover, Co/CeO 2 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/CeO 2 sample where a stable surface performance was observed.