Production of methane and hydrogen via supercritical water gasification of renewable glucose at a relatively low temperature: Effects of metal catalysts and supports

• Renewable CH4/H2 efficiently produced by SCWG of glucose at 500 °C.
• Ni20%Ru2%/Al2O3 exhibited the highest activity/stability for CH4 yield.
• Ru proved to be an excellent promoter to Ni catalyst for SCWG of biomass.
• Ru promotes Ni catalysts by enhancing dispersion/reducibility of metals.

The activities of various supported catalysts were tested in a continuous flow reactor for production of CH4 and H2 from glucose via supercritical water gasification (SCWG) at a relatively low temperature (500 °C). Based on this preliminary study, among all catalysts tested in this study Ni20%Ru2%/γ-Al2O3 catalyst was found to be the most active, achieving complete conversion of all carbon in glucose at 500 °C and a weight-hourly space velocity (WHSV) of 3 h− 1. The addition of 2% Ru to Ni20%/γ-Al2O3 not only suppressed char/tar formation, promoted the carbon gasification efficiently, but also increased methane formation. Moreover, high stability of Ni20%Ru2%/γ-Al2O3 catalyst was demonstrated in the experimental runs for 20 h on-stream. The roles of ruthenium as a co-catalyst in Ni/Al2O3 were found to be not only increasing nickel dispersion, enhancing nickel's reducibility, but also preventing leaching of Al and Ni metals in SCW. However, NiRu supported on either TiO2 and activated carbon led to lower catalytic activity and frequent plugging after only 3 h on-stream.