Catalysed Hydrothermal Carbonization of Woody Biomass and Recycling of Process Liquid

The research introduces catalysed hydrothermal carbonization (CHTC) as a treatment method for woody biomass to produce solid hydrochar as well as value-added compounds (VACs). The hydrochar had higher heating values (HHV) of 28.3 MJ/kg and H/C and O/C ratios similar to coal, when using the liquid:biomass (L:B) ratio of 12:1 for the process. Densified CHTC hydrochar pellets were 97% durable, and hydrophobic when compared with wood pellets and torrefied wood pellets. CHTC has the potential to produce VACs such as glycolic acid, formic acid, acetic acid, levulinic acid, 5-hydroxymethylfurfural, and furfural, from the process liquid effluent. Recycling the process liquid at L:B of 5:1 increased the concentration of the VACs and energy yield of the hydrochar. The production yields of the VACs were dependent upon the L:B ratios, they increased parallel with L:B ratios.