Effect of the average cobalt cluster size on its activity for carbon monoxide methanation

CASTILLO, J.; ARTEAGA, L.; KARELOVIC, A.; FERNÁNDEZ, C.; JIMÉNEZ, R.:
Livro de Atas de XXVI Congresso Ibero-americano de Catálise (CICAT-2018), Setembro 2018, pp 130-135.

Abstract

The effect of cobalt cluster size on the heat of CO adsorption (ECO) and on catalytic activity of Co/SiO2 with different Co mean cluster size (dp = 5nm, 12nm y 35nm) was studied. Catalysts were prepared by incipient wetness; the %Co and the reduction conditions were changed in order to produce catalysts with different dp. The catalysts were characterized by TEM and XRD. In-situ FTIR measurements demonstrated the energetic heterogeneity of cobalt surface, which was fairly represented by the Temkin model. The kinetic data from fixed bed reactor were consistent with a mechanism in which the CO dissociation is assisted by the hydrogen addition and were well represented by a model that considers the effect of CO coverage on Eco. The heat of CO adsorption at low and high CO coverage were regressed with Temkin model by using the independently measured in-situ FTIR and kinetic data; similar values and dependence on Co cluster size were observed for the Eco estimated from both approaching. It was confirmed that the CO hydrogenation reaction is structural sensitive and the increase of TOF with coordination degree of cobalt atoms at surface.

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