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Cobalt hydrotalcites as catalysts for bioethanol steam reforming. The promoting effect of potassium on catalyst activity and long-term stability

Abstract:

Cobalt hydrotalcite-derived catalysts, doped with potassium, are active materials for the ethanol steam reforming reaction. Potassium addition reduces the acid sites number and strength. It acts as a promoter of the ethanol steam reforming (ESR); ethanol conversion is higher at lower temperature, as the amount of potassium at the surface of the catalyst increases. The catalysts are stable for long-term experiments (300h) under high loads of ethanol and bioethanol (0.036g EtOHmin -1, H 2O:CH 3CH 2OH=4:1 molar). Moreover, they generate a low amount of carbon (0.0067g Cg catalyst-1h -1). The catalysts after reaction contain almost exclusively high spin Co 2+ in cobalt oxide (or in (Co,Mg)O); only traces of metallic cobalt are identified by magnetometry, <0.1wt.% Co 0, suggesting that oxidized cobalt is an active species in ESR. © 2012 Elsevier B.V.