Comparative Evaluation of Thermochemical Liquefaction and Pyrolysis for Bio-Oil Production from Microalgae

Bio-oil is the liquid product of thermochemical liquefaction or pyrolysis of biomass. Thermochemical liquefaction (TCL) is a low temperature (250–350 °C) and high pressure (5–20 MPa) process particularly suited for high moisture feedstocks, whereas pyrolysis is accomplished at moderate to high temperatures (400–600 °C) and atmospheric pressure and requires drying of the feedstock. In this paper, we present experimental results that provide a critical comparison of TCL and slow pyrolysis processes for producing bio-oil from algae. TCL experiments were performed in a 1.8-L Parr reactor using algae slurry (80% moisture) and pyrolysis runs were carried out in an 8-L mild steel cubical reactor, using dried algal powder as received (∼4% moisture). Yields and composition of bio-oil, char, gases, and aqueous phase were evaluated and compared for TCL and pyrolysis. TCL resulted in higher bio-oil yields (∼41%), lower char yields (∼6.3%), and lower energy consumption ratio compared to pyrolysis, which resulted in 23–29% bio-oil, and 28–40% solids yields. Bio-oil obtained from TCL was found to have higher energy density and superior fuel properties such as thermal and storage stabilities, compared to pyrolysis bio-oil

MOESM1 of Oleaginous yeast platform for producing biofuels via co-solvent hydrothermal liquefaction

Additional file 1. Supplementary HTL data and experimental information