Supercritical water gasification of an aqueous by-product from biomass hydrothermal liquefaction with novel Ru modified Ni catalysts.

Supercritical water gasification (SCWG) of glucose solution (50-200 g/L), a simulated aqueous organic waste (composed of glucose, acetic acid and guaiacol) and a real aqueous organic waste stream generated from a sludge hydrothermal liquefaction process was performed in a bench-scale continuous down-flow tubular reactor with novel 0.1 RuNi/γ-Al(2)O(3) or 0.1 RuNi/activated carbon (AC) catalyst (10 wt.% Ni with a Ru-to-Ni molar ratio of 0.1). 0.1 RuNi/γ-Al(2)O(3) was very effective in catalyzing SCWG of glucose solution and the simulated aqueous organic waste, attaining an H(2) yield of 53.9 mol/kg dried feedstock at 750°C, 24 MPa and a WHSV of 6h(-1). However, the γ-Al(2)O(3)-supported catalyst was not resistant to the attack of alkali and nitrogen compounds in the real waste during the SCWG of the real aqueous organic waste, whereas the AC-based catalyst exhibited higher stability. This research provides a promising approach to the treatment and valorization of aqueous organic waste via SCWG.