Insight into Catalytic Hydrothermal Liquefaction of Cardboard for Biofuels Production

Catalytic hydrothermal liquefaction (HTL) of cardboard was carried out in a 300 mL Parr batch reactor using 5 wt % Ni(NO3)(2), Ca(NO3)(2), and NiCl2 in a temperature range of 225-300 degrees C for H-2, biocrude, and bio-oil production. A slurry with cardboard, to water weight ratio of 1:30, 1:10, 1;4, or 1:1.5 Was loaded in the reactor and pressurized with N-2 (40 or 200 psi). HTL was performed at various temperatures for 120 min. While HTL was in progress, gas samples were withdrawn periodically and analyzed by GC. The maximum H-2 yield of 11.46 mL/g of cardboard was obtained using Ni(NO3)(2) at 300 degrees C in 30 min. The percent liquefaction of biomass was quantified by TOC. The liquefaction yields were found to be dependent en reaction temperature, residence time, cardboard to water ratio; and operating pressure. The highest biocrude yield of 47.14% was observed at 275 degrees C in 30 min. Light bio-oil (LBO) and heavy bio-oil (HBO) were extracted by dichloromethane and acetone, respectively, and characterized by GC/MS and elemental analyzer. LBO contained mainly C-4-C-11 oxygenated hydrocarbons with a higher heating value (HHV) of 27.71 MJ/kg. HBO consisted of C-17-C-22 oxygenated compounds with a HHV of 29.62 MJ/kg.