Fatty Amide Determination in Neutral Molecular Fractions of Green Crude Hydrothermal Liquefaction Oils From Algal Biomass

Lieve Laurens, Oliver Palardy, Craig Behnke

Research output: Contribution to journalArticlepeer-review

16 Scopus Citations


Even though hydrothermal liquefaction (HTL) is a promising route to produce crude oils (referred to as "green crude"), the molecular composition of the nitrogen fraction of such green crude oils is not fully understood. The goal of this work was to identify and quantify the fraction of fatty amides in green crude oils obtained from five different samples derived from Desmodesmus armatus, Tetraselmis sp., and Chlorella sp. biomass treated under different HTL conditions (260 or 340°C as batch or continuous processes). The goal of this work was to elucidate the nature of the high nitrogen content of the green crude oils. We identified at least 19 distinct fatty amides present in green crude oils and quantified them based on relevant standards in purified fractions after functional group-based separation and enrichment. It was not known how much these compounds contributed to the oils or which molecular fraction they are associated with. We found that fatty amides exclusively partitioned with the neutral fraction of the oils and belonged mainly to one of five categories, based on their functional group substitution, i.e., fatty amides, monomethyl, dimethyl, monoethanolamide, and diethanolamide. The quantification of fatty amides in the neutral oil fraction was based on respective fatty amide standards, after verification of consistency in response factors between molecules with different substitutions of the amide group. We found that the amount of fatty amides found in each of the five samples varied considerably and ranged between 1.4 and 3.0% of the green crude oils, with the highest levels detected in the sample with the highest oil content, after HTL of biomass derived from a nutrient deprived Chlorella sp. culture.

Original languageAmerican English
Pages (from-to)8275-8282
Number of pages8
JournalEnergy and Fuels
Issue number8
StatePublished - 17 Aug 2017

Bibliographical note

Publisher Copyright:
© 2017 American Chemical Society.

NREL Publication Number

  • NREL/JA-5100-68983


  • fatty amides
  • green crude
  • HTL
  • hydrothermal liquefaction


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