Hydrogen and syngas production from gasification of lignocellulosic biomass in supercritical water media

Purpose Novel biomass-processing technologies havebeen recently used for conversion of organic wastes intovaluable biofuels like bio-hydrogen. Agricultural wastes areavailable and renewable energy resources to supply energydemand of the future. The purpose of this study is to investigatethe production of hydrogen-rich syngas from wheatstraw, walnut shell, and almond shell.Methods Supercritical water gasification is a promisingtechnology to convert biomass into useful fuels. Non-catalyticconversion of wheat straw, walnut shell, and almondshell into the hydrogen-rich gas in supercritical water mediawas performed using homemade batch microreactor system.Results Hydrogen gas yields of 6.52, 4.26 and 4.1 mmolper 1 gram of wheat straw, walnut shell, and almond shellwere observed, respectively. In addition, hydrogen andcarbon gasification efficiencies equal to 42.6 and 46.9 %were calculated from gaseous products and elementalanalysis of wheat straw, which were higher than otherfeedstocks’ gasification efficiencies.Conclusion Wheat straw had the highest and walnut shellhad the lowest total gas and hydrogen gas yields. Takinginto account the structural analysis, it was recognized thatfeedstocks with higher cellulose and hemicellulose andlower lignin contents were better gasified due to their easierhydrolysis and higher solubility in water.