Hydrothermal Liquefaction of the Microalgae Phaeodactylum tricornutum: Impact of Reaction Conditions on Product and Elemental Distribution

Abstract

The microalgae Phaeodactylum tricornutum was processed by hydrothermal liquefaction in order to assess the influence of reaction temperature and reaction time on the product and elemental distribution. The experiments were carried out at different reaction times (5 and 15 min) and over a wide range of temperatures (275-420 °C) using a batch reactor system. All fractions were quantified and analyzed in terms of specific elemental concentrations. The highest bio-oil yield (39 %) was obtained at 350 °C when using a reaction time of 15 min. Under these conditions 82 % of the algal calorific value was recovered in the bio-oil fraction. The higher heating value of the bio-oil increased with reaction temperature and reaction time. The elemental analysis was used to map the distribution of elements in the obtained fractions with increasing temperature. Generally, most of the potassium, sodium, nitrogen, phosphorus, and sulfur were recovered in the aqueous fraction. The solid residue was found to primarily consist of a calcium phosphate compound.

Feedstock-Dependent Phosphate Recovery in a Pilot-Scale Hydrothermal Liquefaction Bio-Crude Production

“…While the multivalent ions demonstrated a tendency to precipitate under the studied hydrothermal conditions-which was reflected in the fact that calcium, magnesium, iron, and aluminum were mainly recovered in the HTL solid phase-the monovalent ions (K + , Na + ) remained dissolved in the HTL liquid phase. A similar tendency has been described in references [66,67]. The nitrogen that was recovered in the HTL liquid phase, which resulted from the degradation of proteins under hydrothermal conditions [15,26], was clearly higher for HTL-SPR-LP than for HTL-PSS-LP.…”

Valorization of Waste From Agro-Industry Using Thermo-Chemical Treatments

“…Comparing the two biomasses with the coffee husk would yield a biofuel with the lowest sulphur content of 0.066%. The sulphur content expected for bio-oils is <0.05% m/m, where both biomass are above this value by which may require a process of desulfurization [22].…”

“…These may be due to the fact that in these treatments are conditions that give the water properties features that allow you to more easily carry depolymerization, hydrolysis reactions, and decomposition of the biomass [22]. On the band of the C=C aromatic notes a small shoulder in the region of 1700 cm -1 , which indicates that the biocarbon from hydrothermal reactions with carbonyl groups.…”

A Review of the Biofuel Yield in Hydrothermal Liquefaction of Different Microalgae

“…Vardon et al [12] obtained the conclusion that raw Scenedesmus had the highest yield of HTL bio-oil (45%) and about defatted Scenedesmus (36%) during the experiments of comparing HTL with slow pyrolysis. Christensen et al [28] processed Phaeodactylum by HTL in order to assess the influence of reaction temperature and reaction time on the product and elemental distribution and found that the highest bio-oil yield can reach 39% under the condition of 350 °C and 15 min. Tian et al [29] focused on the HTL of harvested algae from Dianchi in China and obtained the highest biofuel yield (18.4%) at 300 °C, 60 min and 20% solid concentration.…”