Kinetics study of the hydrothermal liquefaction of the microalga Aurantiochytrium sp. KRS101

Abstract

We investigated the hydrothermal liquefaction (HTL) of microalgal Aurantiochytrium sp. KRS101 at various reaction temperatures (250∼400 °C) and reaction times (10∼60 min). The product distributions of bio-oil, aqueous-phase, and gaseous products were strongly affected by reaction temperature and time. The highest bio-oil yield of 51.22 wt% was obtained at 400 °C for 10 min. A general quantitative kinetic model was applied to the hydrothermal liquefaction of microalgae, in which aqueous-phase product (AP), bio-oil, and gas were formed from the decomposition of carbohydrates, lipids, and proteins in biomass cells. The rate constants of the model were determined by minimizing the least-squares error between the experimental and calculated data using a MATLAB optimization function. The results show that the model accurately captures the trend in the experimental data. The kinetics rate constants indicate that the formations of bio-oil and aqueous-phase products from decomposition of proteins, lipids, and carbohydrates are the dominant reaction pathways. The kinetic parameters calculated from the model were utilized to explore the parameter space in order to predict liquefaction product yields.