Sub- and Supercritical Hydrothermal Liquefaction of Oil Palm Biomass to Bio-oil

3 types of Malaysian oil palm biomass with different lignocellulosic contents are liquefied using sub- and supercritical water to produce bio-oil. It is found that the optimum liquefaction conditions for the three types of biomass (EFB, PMF and PKS) using water are at supercritical conditions. PKS which consists of highest lignin content yields the maximum bio-oil of about 41.3 wt % at temperature of 450 °C, followed by PMF and EFB obtaining bio-oil yields of about 39.6 wt % and 37.4 wt % at temperatures of 450 °C and 390 °C, respectively.