(427c) Hydrogen Production From Liquefied Switchgrass in Supercritical Water Over Ru, Ni, and Co Catalysts

Switchgrass is a renewable high yield energy crop with the potential to offset our fossil fuel usage and reduce carbon emissions. In this work, switchgrass was liquefied in subcritical water ( T= 300°C, P=100 bar) in a batch reactor to give an aqueous solution of oxygenated hydrocarbons containing ~1.5 wt% C designated as biocrude. Biocrude was then subject to reforming in supercritical water to produce hydrogen. A suite of nine catalysts designated as Metal/Support (M=Ru, Ni, Co; S=TiO2, ZrO2, MgAl2O4) was prepared and evaluated in the supercritical water gasification of liquefied biomass (T=600°C, P=250 bar, WHSV=9h-1). Activity of the catalysts was evaluated in terms of hydrogen yield, gasification efficiency, and tendency towards char formation, as measured by the degree of closure of a carbon balance around the process. Spent catalysts were characterized by the BET method and XRD to evaluate the stability of the support materials in the SCW environment. The highest gasification efficiency was obtained over Ru/ZrO2, while the highest hydrogen yield was seen with Ni/ZrO2.