A general reaction network and kinetic model of the hydrothermal liquefaction of microalgae Tetraselmis sp.

In this work, the hydrothermal liquefaction (HTL) of microalgal Tetraselmis sp. was conducted at various reaction temperatures (250-350°C) and reaction times (10-60min). A general reaction network and a quantitative kinetic model were proposed for the HTL of microalgae. In this reaction network, the primary decomposition of lipids, proteins, and carbohydrates generated heavy oil (HO), light oil (LO), and aqueous-phase (AP) products. Then, reversible interconversions and further decomposition of these product fractions to produce gas product were followed. The model accurately captures the trends observed in the experimental data. Analyses of the kinetic parameters (reaction rate constants and activation energies) suggested the dominant reaction pathways as well as the contribution of the biochemical compositions to the bio-oil yield. Finally, the kinetic parameters calculated from the model were utilized to explore the parameter space in order to predict the liquefaction product yields depending on the reaction time and temperature.