Hydrothermal liquefaction of lignocellulosic biomass with potassium phosphate and iron and their binary mixture: A comprehensive investigation on the yields and compositions of biocrude and solid residue

Hydrothermal liquefaction of corn, soybean, rice and wheat straws with K₃PO₄, Fe and Fe + K₃PO₄ at 320 °C for 30 min was examined. The addition of K₃PO₄ led to the highest biocrude yields from hydrothermal liquefaction of rice straws (39.20 wt%). Particularly, the biocrude yields from K₃PO₄-catalyzed hydrothermal liquefaction of corn and rice straws were ∼ 10 wt% higher than those from non-catalytic run (19.4 and 27.8 wt%). Catalytic hydrothermal liquefaction with K₃PO₄ had minimal impact on the elemental compositions of biocrudes and solid residue. Furthermore, K₃PO₄ promoted the enrichment of low-boiling components in biocrudes by 2.02 wt%. for hydrothermal liquefaction of wheat straw. Moreover, the incorporation of K₃PO₄ induces the occurrence of dense porous structure on the surface of solid residue, making it highly suitable as an adsorbent or catalyst carrier. Finally, potential reaction network and mechanisms of catalytic hydrothermal liquefaction of straw have been proposed and discussed detailly.