Hydrogen production from supercritical water gasification of canola residues

Canola hull, meal and straw are abundantly available as low-value agricultural residues in Canada. These lignocellulosic feedstocks have the potential for the generation of biofuels as alternatives to fossil fuels. Super-critical water gasification is an emerging hydrothermal process for the conversion of recalcitrant biomasses into value-added hydrogen with the application of water beyond its critical temperature and pressure. This study focuses on the comparative investigation of supercritical water gasification of canola residues for H2 production through optimization of process temperature (350-500 degrees C), reaction time (20-80 min) and feedstock concen-tration (10-25 wt%) at a constant pressure of 23-25 MPa. Supercritical water gasification of canola straw resulted in a high H2 yield of 7.1 mmol/g to 6.2 mmol/g of H2 from canola hull and 5.5 mmol/g of H2 from canola meal at a temperature, reaction time and feedstock concentration of 500 degrees C, 40 min and 20 wt%, respectively. Furthermore, H2 yield and total gas yield from canola straw were maximized to 8.1 mmol/g and 29.7 mmol/g at the optimized supercritical water gasification conditions of 500 degrees C, 60 min and 10 wt%. Hydrochar obtained at high gasification temperatures also revealed aromatic carbon structures and thermal stability due to dehydrogenation, decarboxylation, deamination and aromatization. The overall results demon-strated the potential of supercritical water gasification as an evolving hydrothermal process to convert ligno-cellulosic biomass into high-value H2-rich gas.