Hydrothermal liquefaction of low-lipid algae Nannochloropsis sp. and Sargassum sp.: Effect of feedstock composition and temperature.

Sirong He, Minfeng Zhao, Jinglan Wang, Zhanjun Cheng, Beibei Yan, Guanyi Chen

The Science of the total environment 2020 Apr 10

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Low-lipid content algae have demonstrated potential in the bio-crude production because of their high yield and robust ability to adapt to hostile cultivation environment in mass cultivation. Hydrothermal liquefaction (HTL) technology is an effective method to convert wet algae to bio-crudes directly. In this study, the HTL processes of two low-lipid content algae, Nannochloropsis sp. and Sargassum sp., were investigated under various reaction temperatures (260-320 °C). Results showed that the bio-crudes yield of Nannochloropsis sp. (39.05 wt% to 54.11 wt%) was significantly higher than that of Sargassum sp. (3.11 wt% to 9.49 wt%). The higher heating value of Nannochloropsis sp. (35.92 MJ/kg to 37.88 MJ/kg) were also slightly higher than that of Sargassum sp., (33.63 MJ/kg to 35.23 MJ/kg). GC-MS analyses showed that Nannochloropsis sp. bio-crude mainly contained amides and N-heterocyclic compounds while Sargassum sp. bio-crude mainly contained N-heterocyclic compounds and ketones. Alcohols were the major aqueous phase compounds for both algae. For Nannochloropsis sp., glycerin accounted for the largest proportion in alcohols, while dianhydromannitol and 1,5-anhydro-d-mannitol were the major alcohols component for Sargassum sp. Based on the compositions of the HTL products and the feedstock, a reaction pathway network of the HTL process of low-lipid algae was proposed in this study. Amino acids related interactions like acylation and Maillard reaction were prominent in HTL process of these two algae, which effectively converted protein and carbohydrate compounds into bio-crudes. Copyright © 2019. Published by Elsevier B.V.

Citation

Sirong He, Minfeng Zhao, Jinglan Wang, Zhanjun Cheng, Beibei Yan, Guanyi Chen. Hydrothermal liquefaction of low-lipid algae Nannochloropsis sp. and Sargassum sp.: Effect of feedstock composition and temperature. The Science of the total environment. 2020 Apr 10;712:135677