Catalytic gasification of glucose to H2 in supercritical water

• Supercritical gasification of glucose was studied in a batch reactor.
• Increase in process temperature and water to biomass ratio increased H2 yield.
• Use of catalysts increased the H2 yield in product by 52–135%.
• NaOH showed the best catalytic activity for H2 production.
• The higher heating value of oil product was ~ 33–35 MJ/kg for catalytic runs.

Gasification of glucose in supercritical water with and without catalysts (NaOH and Ni based) was investigated at 400 °C and 500 °C with a residence time of 30 min. The products from glucose gasification without catalyst consist of ~ 8–17 wt.% gas, 21–24 wt.% solid, 9–16 wt.% acetone phase and 8–10 wt.% water phase. As expected, all the gas product yields increased by an increase in process temperature and higher water to biomass ratio benefits the yields of gas phase and water phase. For the experimental runs with catalysts, NaOH had the best activity for improving H2 formation, the H2 yield increased by 135% with NaOH compared to that for run without catalyst at 500 °C with water to biomass ratio of 3. At the same operating conditions, the presence of Ni/activated carbon (AC) contributed to 81% increase in H2 yield, followed by 62% with Ni/MgO, 60% with Ni/CeO2/Al2O3 and 52% with Ni/Al2O3. The net effect of Ni was studied by using activated carbon and Ni/AC at 500 °C with water to biomass ratio of 7 for 30 min. The results showed that the hydrogen production was further increased by 6.9% with activated carbon and 36.9% with Ni/AC.