Modeling the effects of microalga biochemical content on the kinetics and biocrude yields from hydrothermal liquefaction

Abstract

A kinetic model for the hydrothermal liquefaction (HTL) of microalgae was developed and its performance in predicting biocrude yields was tested. Kinetic interactions between algal proteins, carbohydrates, and lipids were also included for the first time. These interactions provided a better fit of the data used to determine model parameters, but the kinetics model lacking interactions provided a better prediction of published biocrude yields. This model predicted 70 published biocrude yields to within ±5wt% given the biochemical composition of the alga and the HTL temperature and time as model inputs. Forty-two other published biocrude yields were predicted to within ±10wt%. The model accurately predicts that feedstocks richer in proteins or lipids give higher biocrude yields than those abundant in carbohydrates. This updated model better predicts the combined influences of HTL reaction conditions and algae biochemical composition on HTL biocrude yields than any other model currently available.

Keywords: Algal liquefaction; Biocrude-oil; Subcritical water.