Hydrothermal Conversion of Biomass into
Fuel and Fine Chemicals
Chitra Devi Venkatachalam, Mothil Sengottian,
and Sathish Raam Ravichandran
Contents
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 202
2 Hydrothermal Conversion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205
2.1 Hydrothermal Carbonization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206
2.2 Hydrothermal Liquefaction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206
2.3 Hydrothermal Gasification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207
2.4 Conversion Chemistry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207
3 Hydrothermal Conversion Process Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209
3.1 Effect of Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210
3.2 Effect of Hydrothermal Media . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213
3.3 Effect of Biomass to Solvent Ratio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213
3.4 Effect of Catalyst . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215
4 Biomass to Fuel . . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . 216
5 Biomass to Fine Chemicals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 221
6 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 221
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 221
Abstract Hydrothermal conversion is an important thermochemical conversion
technique that is used to convert waste biomass into valuable products or biofuel.
The process is usually performed in the presence of water at high temperature and
high pressures. The biomass is depolymerized to form three phases such as biocrude,
biogas, and biocarbon into small components in water. Based on the process
conditions (temperature, pressure, catalyst, and time), the yield of the phases varies
accordingly. Comparing to other thermochemical conversion techniques like combustion, pyrolysis, and gasification, the hydrothermal conversion is highly appropriate for handling biomass with high moisture content. According to the
physicochemical properties of water, the process can be classified as hydrothermal
C. D. Venkatachalam (*), M. Sengottian, and S. R. Ravichandran
Kongu Engineering College, Erode, Tamil Nadu, India
e-mail: erchitrasuresh@gmail.com
Manuel Jerold, Santhiagu Arockiasamy, and Velmurugan Sivasubramanian (eds.),
Bioprocess Engineering for Bioremediation: Valorization and Management
Techniques, Hdb Env Chem (2020) 104: 201–224, DOI 10.1007/698_2020_583,
© Springer Nature Switzerland AG 2020, Published online: 8 July 2020
201
Fuel and Fine Chemicals
Chitra Devi Venkatachalam, Mothil Sengottian,
and Sathish Raam Ravichandran
Contents
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 202
2 Hydrothermal Conversion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205
2.1 Hydrothermal Carbonization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206
2.2 Hydrothermal Liquefaction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206
2.3 Hydrothermal Gasification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207
2.4 Conversion Chemistry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207
3 Hydrothermal Conversion Process Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209
3.1 Effect of Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210
3.2 Effect of Hydrothermal Media . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213
3.3 Effect of Biomass to Solvent Ratio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213
3.4 Effect of Catalyst . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215
4 Biomass to Fuel . . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . 216
5 Biomass to Fine Chemicals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 221
6 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 221
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 221
Abstract Hydrothermal conversion is an important thermochemical conversion
technique that is used to convert waste biomass into valuable products or biofuel.
The process is usually performed in the presence of water at high temperature and
high pressures. The biomass is depolymerized to form three phases such as biocrude,
biogas, and biocarbon into small components in water. Based on the process
conditions (temperature, pressure, catalyst, and time), the yield of the phases varies
accordingly. Comparing to other thermochemical conversion techniques like combustion, pyrolysis, and gasification, the hydrothermal conversion is highly appropriate for handling biomass with high moisture content. According to the
physicochemical properties of water, the process can be classified as hydrothermal
C. D. Venkatachalam (*), M. Sengottian, and S. R. Ravichandran
Kongu Engineering College, Erode, Tamil Nadu, India
e-mail: erchitrasuresh@gmail.com
Manuel Jerold, Santhiagu Arockiasamy, and Velmurugan Sivasubramanian (eds.),
Bioprocess Engineering for Bioremediation: Valorization and Management
Techniques, Hdb Env Chem (2020) 104: 201–224, DOI 10.1007/698_2020_583,
© Springer Nature Switzerland AG 2020, Published online: 8 July 2020
201