Elemental migration and characterization of products during hydrothermal liquefaction of cornstalk

Biofuel production from lignocellulosic biomass through hydrothermal liquefaction (HTL) is a promising direction. This study characterized the products and investigated the elemental migration during the HTL of cornstalk at seven different operation temperatures (210–375 °C). The biocrude oil yield significantly increased from 7.04% (210 °C) to 23.32% (290 °C) as the temperature increased, and decreased to 21.07% when further increased to 375 °C. A carbon recovery of 11.03–38.69%, and a hydrogen recovery of 7.77–25.61% were achieved in the biocrude oil. Hydrogen (27.87–70.94%) and nitrogen (74.56–81.76%) were effectively recovered in the aqueous phase. GC–MS, HPLC, TGA and FT-IR analysis indicated that major organic compounds in the biocrude oil were interestingly similar between 210 °C and 270 °C. The identified compounds included hydrocarbons, esters and carboxylic acid. The calculative yields of biocrude, hydrogen, methane and biochar reached 7.04–23.32, 0.07–0.29, 7.12–12.08 and 3.01–22.42 t/100 t cornstalks, respectively.