452426 Hydrogen Production from Lignocellulosic Biomass Residues Via Gasification in Supercritical Waterï¼šCatalyst Activity and Process Optimization Study
Hydrogen production from biomass is an attractive alternative for clean energy generation. Supercritical water gasification (SCWG) is a promising technology for effectively conversion of wet biomass into a pressurized, clean and hydrogen rich gas . Catalysis is crucial for achieving promising conversion of biomass at lower temperature, which could bringing down the cost of this process .
In this study, firstly, characterization and evaluation for two groups of catalysts for hydrogen production via SCWG process are carried out. For Ni-Co/Mg-Al catalysts, it was found that higher hydrogen yield could be correlated to strong acidic sites in the range of 400 -600 °C. For catalyst preparation co-precipitation is better than impregnation in terms of hydrogen yield. Also, for Ni/TiO2 catalysts, 5 wt% Ni loading is optimum for hydrogen production, however, adding promoters such as Ru, Co, Ce, Mg or change in the active metal to Ru at 5 wt% loading did not improve the hydrogen yield.
By catalysts screening, K2CO3 and 20Ni-0.36Ce/Al2O3 were identified as the best catalysts. Then, an optimization study relating the effects of different parameters based on Taguchi experimental design was conducted, and biomass including wheat straw, canola meal, and timothy grass were used as feedstock. The order of relative importance for process parameters for hydrogen production is: temperature ˃ catalyst loading ˃ catalyst type ˃ biomass type. High temperature (~650 °C), and high catalyst loading (~100%) are favorable for hydrogen production. Using different waste biomass, the average hydrogen yield was in the order of: canola meal > wheat straw > timothy grass.
Supercritical water (SCW), hydrogen, biomass, catalysis
 R.M. Navarro, M.C. Sanchez-Sanchez, M.C. Alvarez-Galvan, F.d. Valle, J.L.G. Fierro. Hydrogen production from renewable sources: biomass and photocatalytic opportunities. Energy & Environmental Science. 2 (2009) 35-54.
 Y. Guo, S.Z. Wang, D.H. Xu, Y.M. Gong, H.H. Ma, X.Y. Tang. Review of catalytic supercritical water gasification for hydrogen production from biomass. Renewable and Sustainable Energy Reviews. 14 (2010) 334-43.