Supercritical water gasification of waste water produced from hydrothermal liquefaction of microalgae over Ru catalyst for production of H2 rich gas fuel

Ru supported on activated carbon (C), Al 2 O 3 , CeO 2 , MgO, TiO 2 , and ZrO 2 were prepared and employed to boost supercritical water gasification (SCWG) of microalgae hydrothermal liquefaction (HTL) downstream water at 600 °C for 1 h. Effects of catalysts, water density, and Ru/C loading on total organic carbon (TOC) reduction, carbon gasification efficiency (CGE), and gas yield were examined. All the Ru catalysts showed a positive effect on TOC reduction and converted organics in the HTL downstream water to fuel gas, with H 2 and CH 4 as the two most abundant component. With the addition of Ru/C, almost complete removal of TOC, the highest CGE, and H 2 yield were achieved due to its largest metal dispersion. With the addition of Ru/C, increasing water density and catalyst loading favored TOC reduction and CGE increase as well as the total gas yield. The highest H 2 content of 50% and yield of 2.62 mmol/g (aq.) were obtained at the highest catalyst loading of 12.0 mg (Ru/C) /mL (aq.) . This study suggested that SCWG with the addition of Ru/C was a promising strategy to produce fuel gas rich in H 2 , from the organics in the microalgae HTL downstream water.