Influence of biochemical composition during hydrothermal liquefaction of algae on product yields and fuel properties

Abstract

Hydrothermal liquefaction (HTL) of nine algae species were performed at two reaction temperatures (280 and 320°C) to compare the effect of their biomass composition on product yields and properties. Results obtained after HTL indicate large variations in terms of bio-oil yields and its properties. The maximum bio-oil yield (66wt%) was obtained at 320°C with a high lipid containing algae Nannochloropsis. The higher heating value of bio-oils ranged from 31 to 36MJ/kg and around 50% of the bio-oils was in the vacuum gas oil range while high lipid containing algae Nannochloropsis contained a significant portion (33-42%) in the diesel range. A predictive relationship between bio-oil yields and biochemical compositions was developed and showed a broad agreement between predictive and experimental yields. The aqueous phases obtained had high amount of TOC (12-43g/L), COD (35-160g/L), TN (1-18g/L), ammonium (0.34-12g/L) and phosphate (0.7-12g/L).

Effects of separation methods on yield and quality of biocrude after thermochemical liquefaction of marine microalgae

“…Moreover, the energy recovery corroborates with biocrude yields. In this study, ER were 71% for M1, 67% for M2, 75% for M3, 89% for M4 and 86% for M5 and were within the range of reported scientific literature [3,5,27]. Skakya et al, [5] reported ER of 47% for Chlorella sp., 78% for Scenedesmus sp.…”

“…The higher heating value (HHV), chemical energy recovered in biocrude, and the hydrogen-to-carbon ratio were determined in accordance to methods explained previously [20,24]. Sample of biocrudes (diluted to 2.5v/v% with acetone) were analysed with Gas Chromatography-Mass Spectrometer (GC-MS) (Agilent Technologies 6890 N, equipped with Agilent HP-5 capillary column of 50m×200µm×0.33µm) in accordance to the method reported previously [5,16].…”

“…Biocrude obtained from HTL, likewise pyrolysis of algae had water content [1,15]. Shakya et al, [5] reported that biocrude contains about 4% to 9% water content, which is estimated alongside its yield. Occurrence of water molecules in biocrude are in the form of oxygenated compounds such as aldehydes, carboxylic acids, esters, and ketones.…”

“…Importantly, HTL obviates high energy-intensive step associated with drying of biomass as normally applied in other thermochemical processes such as gasification and pyrolysis [3,4]. Products obtained from HTL of microalgae are biocrude, solid residue, aqueous and gas phases [5,6]. Typically, HTL of algae biomass first produces liquid product mixture, and it is from it that the HTL products are obtained after series of extraction protocols using organic solvent.…”

Catalytic hydrothermal liquefaction of Spirulina platensis : Focusing on aqueous phase characterization

“…In typical liquefaction, the biomass feedstock is decomposed into different product fractions, such as aqueous phase, biocrude, gaseous phase, and the solid residue . The biocrude is a complex mixture of organic compounds, including oxygen and nitrogen‐containing compounds, esters, hydrocarbons, and organic acids . So far, the biocrude is thought to be a promising substitution of fossil fuel due to its high overall heating values and renewable characteristics.…”