Single- and two-step hydrothermal liquefaction of microalgae in a semi-continuous reactor: Effect of the operating parameters.
This work investigated an influence of operating conditions on the biocrude yield and properties obtained from hydrothermal liquefaction (HTL) of Coelastrum sp. microalgae in a two-step sequential HTL (THTL) and a single-step HTL (SHTL) using a semi-continuous system. A higher biocrude yield with a lower nitrogen content was obtained with the THTL process than the SHTL one. The operating temperature, pressure and water flow rate were sequentially varied in a univariate analysis for a 2 h reaction time to optimize the obtained biocrude yield. Increasing the temperature improved the biocrude yield, but the second step temperature should not be higher than 320 °C to prevent the thermal cracking to gaseous compounds. The optimal conditions of THTL were preliminarily temperature of 200 and 320 °C and pressure of 7 and 20 MPa for the first and second step, respectively, both with a water flow rate of 0.50 mL/min.
Department of Petrochemical and Polymer Science, Faculty of Science, Chulalongkorn University, 254 Phayathai Road, Bangkok 10330, Thailand.
Keerati
K
Prapaiwatcharapan
Faculty of Engineering and Architecture, Rajamangala University of Technology Tawan-ok, Uthenthawai Campus, 225 Phayathai Road, Bangkok 10330, Thailand.
Sasithorn
S
Sunphorka
Fuels Research Center, Department of Chemical Technology, Faculty of Science, Chulalongkorn University, 254 Phayathai Road, Bangkok 10330, Thailand; Center of Excellence on Petrochemical and Materials Technology, 7th Floor, Chulalongkorn University Research Building, Soi Chula 12, Phayathai Road, Bangkok 10330, Thailand. Electronic address: prapan.k@chula.ac.th.
Prapan
P
Kuchonthara
PTT Research and Technology Institute, Phahon Yothin Road, Wangnoi, Ayutthaya 13170, Thailand.
Kunn
K
Kangvansaichol
Fuels Research Center, Department of Chemical Technology, Faculty of Science, Chulalongkorn University, 254 Phayathai Road, Bangkok 10330, Thailand; Center of Excellence on Petrochemical and Materials Technology, 7th Floor, Chulalongkorn University Research Building, Soi Chula 12, Phayathai Road, Bangkok 10330, Thailand.
Napida
N
Hinchiranan
D018533:Biomass; D019149:Bioreactors; D058086:Microalgae / Q000378:metabolism*; D013696:Temperature
Algae; Biocrude yield; Hydrothermal liquefaction; Semi-continuous reactor