Hydrothermal liquefaction of wet biomass in batch reactors: Critical assessment of the role of operating parameters as a function of the nature of the feedstock

A scientometric analysis of articles published from 1986 to 2022 on batch hydrothermal liquefaction of microalgae, macroalgae, lignocellulosic biomass, sewage sludge and organic wastes in water was performed. We found that biocrude yield can be correlated with the kinetic severity factor (KSF) and scattering of experimental data increases in the supercritical region probably for uncertainty in the medium density affecting the kinetics of reactions involved in the process. The level of correlation and the yield increased when fast heating rates of the reactor, higher than 25 ◦C/min, were adopted. Energy recovery of biocrude obtained in fast heating experiments changes linearly with biocrude yield independently on the adopted biomass. From this analysis, it seems interesting to assess more systematically the role of KSF, nominal density of reaction medium and heating rate with costless not algal biomass.