Carbon Nanofibers-supported Non-noble Metal Catalysts for the Aqeous-phase Reforming of Ethylene Glycol

Abstract

The applicability of carbon nanofibers-supported Ni and Cu metal catalysts was studied in the aqueous-phase reforming of ethylene glycol for the sustainable production of hydrogen. Catalyst performance and stability were examined (at 503K and autogenic pressure in a batch reactor) relative to a commercial alumina supported Pt catalyst – the most selective catalyst reported to date. Catalytic performance analysis indicated similar activity for 11.7wt% Ni and 5.0wt% Pt catalysts and low activity for 16.6wt% Cu catalysts. However, severe deactivation via metal particle growth and leaching of the catalysts systems was observed, especially for Ni. Hence, the influence of the reactant concentration, gas phase composition and the pH of the reaction medium on Ni catalyst stability were studied. Subsequent analysis indicated significant reduction of catalyst deactivation, in particularly by the addition of KOH. It appears that the latter effectively neutralises the produced acidic by-products during operation and consequently prevents the formation and leaching of soluble Ni species. These results potentially signify the inhibition of metal particle growth via the Ostwald ripening mechanism under aqueous-phase reforming conditions. In addition, a substantial increase in activity and product yield were observed in the presence of KOH over Ni and Cu catalysts as well as a decline in the production of CH4 for the Ni. Accordingly, Ni/CNF proved to be to be a promising catalyst in the aqueous-phase reforming of ethylene glycol in the presence of KOH.