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

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• 作者：Ra¨²l Espinal ; Elena Taboada ; Elies Molins ; Ricardo J. Chimentao ; Francesc Medina ; Jordi Llorca
• 关键词：Hydrogen ; Ethanol reforming ; Bioethanol ; Cobalt catalyst ; Hydrotalcite-derived catalyst ; Honeycomb
• 刊名：Applied Catalysis B: Environmental
• 出版年：2012
• 出版时间：30 October, 2012
• 年：2012
• 卷：127
• 期：Complete
• 页码：59-67
• 全文大小：1279 K

文摘

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 (300 h) under high loads of ethanol and bioethanol (0.036 g_EtOH min^?1, H₂O:CH₃CH₂OH = 4:1 molar). Moreover, they generate a low amount of carbon (0.0067 g_C g_catalyst^?1 h^?1). The catalysts after reaction contain almost exclusively high spin Co²⁺ in cobalt oxide (or in (Co,Mg)O); only traces of metallic cobalt are identified by magnetometry, <0.1 wt. % Co⁰, suggesting that oxidized cobalt is an active species in ESR.