Hydrothermal liquefaction of algal biomass is growing as a promising technology for the production of liquid biofuels in the renewable energy sector. The potential of this technology under varied process conditions has been extensively demonstrated worldwide. Recent developments have revealed that the feedstock quality and extraction solvents have a considerable effect on the biocrude quality and yield. Algal lipids and proteins contribute significantly to biocrude formation, while carbohydrates contribute mainly to the production of gaseous products. However, the challenges associated with high N/C and O/C ratios in biocrude derived from proteinaceous biomass need to be addressed. Recently, co-liquefaction of carbonaceous biomass with different biochemical compositions has proven promising in biocrude upgradation. The most contemporary research also revealed that solvents as a co-solvent and/or extraction agent have the most significant effect on biocrude quality and yield in the HTL mixture. These solvents could also intensely influence the properties and distribution of energy-dense compounds in the biocrude. The present paper extensively reviews the effect of feedstock composition on HTL biocrude formation and its characteristics based on the information collected from more than 150 scientific resources published between 2010 and 2021. Furthermore, the role of solvents as reaction medium and extraction agent on biocrude yield and composition has been critically reviewed. Future perspectives and challenges in the use of approaches for improving biocrude formation are also discussed. • Biochemical composition and extraction solvents influence algal biocrude yield and quality. • The use of solvents could play imperative role as co-solvent and extraction agent for enhancing biocrude yield and quality. • Much attention needed to improve the N/C & O/C ratio of algal crude to match fossil crude standards. • Feedstock characteristics and extraction solvents influence the distribution of compounds in the biocrude. • The exploration of appropriate extraction solvents is still in the early-stage and needs developments. 

Hydrothermal liquefaction of algal feedstocks: The effect of biomass characteristics and extraction solvents

Upgrading Pyrolysis Oil by Catalytic Hydrodeoxygenation Reaction in Supercritical Ethanol with Different Hydrogen Sources

ABSTRACT The authors have investigated hydro-liquefaction of Lemna minor (duckweed) aquatic biomass and a hydrogen-donor solvent, methanol, at temperatures of 180 °C, 200 °C and 220 °C and final reactor pressure values of 70, 80 and 90 bar. The rise in reactor pressure for all reaction temperatures led to an increase in biocrude yield with a maximum higher heating value of 22.19 MJ/kg, while the biochar also depicted its potential to be used in varied applications and as a bio-refinery feedstock. Fourier Transform Infrared Spectroscopy and Gas Chromatography Mass Spectrometry analysis of biocrude indicated the presence of esters and long chain alkanes, ethers, phenols, etc. The main finding of this work disclosed that fuel properties of the present biocrude (without any catalyst) were better than their non-catalytic and hydro-catalytic bio-oil counterparts obtained from similar biomass at a pyrolysis temperature of 550 °C.

Hydro-liquefaction of Lemna minor (Duckweed) with hydrogen-donor solvent at varying hydrogen pressures

Vacuum fractional distillation of biocrude oil and the immobilization of harmful metal

Upgrading pyrolysis oil by catalytic hydrodeoxygenation reaction in supercritical ethanol with different hydrogen sources

Influence of extraction solvents on the recovery yields and properties of bio-oils from woody biomass liquefaction in sub-critical water, ethanol or water–ethanol mixed solvent

Sida Xu

Papers

Influence of extraction solvents on the recovery yields and properties of bio-oils from woody biomass liquefaction in sub-critical water, ethanol or water–ethanol mixed solvent