title: Thermochemical conversion of raw and defatted algal biomass via hydrothermal liquefaction and slow pyrolysis.
abstract: Thermochemical conversion is a promising route for recovering energy from algal biomass. Two thermochemical processes, hydrothermal liquefaction (HTL: 300 °C and 10-12 MPa) and slow pyrolysis (heated to 450 °C at a rate of 50 °C/min), were used to produce bio-oils from Scenedesmus (raw and defatted) and Spirulina biomass that were compared against Illinois shale oil. Although both thermochemical conversion routes produced energy dense bio-oil (35-37 MJ/kg) that approached shale oil (41 MJ/kg), bio-oil yields (24-45%) and physico-chemical characteristics were highly influenced by conversion route and feedstock selection. Sharp differences were observed in the mean bio-oil molecular weight (pyrolysis 280-360 Da; HTL 700-1330 Da) and the percentage of low boiling compounds (bp<400 °C) (pyrolysis 62-66%; HTL 45-54%). Analysis of the energy consumption ratio (ECR) also revealed that for wet algal biomass (80% moisture content), HTL is more favorable (ECR 0.44-0.63) than pyrolysis (ECR 0.92-1.24) due to required water volatilization in the latter technique.
authors.affiliation: Dept. of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, 205 N. Mathews Ave., Urbana, IL 61801, United States. dvardon2@illinois.edu
authors.forename: Derek R
authors.initials: DR
authors.lastname: Vardon
authors.forename: Brajendra K
authors.initials: BK
authors.lastname: Sharma
authors.forename: Grant V
authors.initials: GV
authors.lastname: Blazina
authors.forename: Kishore
authors.initials: K
authors.lastname: Rajagopalan
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Strathmann
mesh_terms: D056804:Biofuels / Q000032:analysis; D018533:Biomass; D001709:Biotechnology / Q000379:methods*; D002850:Chromatography, Gel; D003198:Computer Simulation; D057168:Distillation; D004602:Elements; D008055:Lipids / Q000302:isolation & purification*; D009682:Magnetic Resonance Spectroscopy; D008970:Molecular Weight; D010938:Plant Oils / Q000737:chemistry; D044444:Scenedesmus / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D053545:Spirulina / Q000737:chemistry*; D013696:Temperature; D013816:Thermodynamics; D014867:Water / Q000737:chemistry*
chemical_list: D056804:Biofuels; D004602:Elements; D008055:Lipids; D010938:Plant Oils; D014867:Water