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Title: Characterization of the Aqueous Fractions from Hydrotreatment and Hydrothermal Liquefaction of Lignocellulosic Feedstocks

In this study the aqueous phases resulting from the hydrothermal liquefaction of biomass and the hydrotreatment of fast pyrolysis bio-oils were analyzed via TC, COD, GC-MS, GC-FID, HPLC, and ICP-OES to determine the organic and inorganic species present and the quantitative amounts of each. This work is necessary to address a significant knowledge gap in the literature related to the aqueous phases from thermochemical processes. Results showed that water from the hydrotreatment of eight different bio-oils contained less than 1 wt% total carbon, in many cases less than 0.2%. Negligible organic carbon was observed. Hydrothermal liquefaction samples contained between 1-2 wt% carbon, accounting for 34 – 45% of the total carbon sent to the reactor. The majority of this carbon was present as acids, with glycolic acid and acetic acid having the highest concentrations. Alcohols, specifically methanol and ethanol, were also present. Numerous ketones were observed, consisting of mainly acetone and cyclopenta-ones. The amount of the total carbon identified and quantified in the HTL samples ranged from 64 – 82%. Inorganic species present in the HT samples were sodium, silicon, and sulfur. The highest levels of sulfur were observed in the grasses and agricultural residue (corn stover). The HTL samplesmore » exhibited much higher inorganic content, with very high levels of sodium and potassium. Alkali and alkali earth metals, as well as sulfur, were also present at levels high enough to raise concerns for the use of catalysts in downstream upgrading or reforming processes.« less
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Resource Type:
Journal Article
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Journal Name: Biomass & Bioenergy, 74:162-171
Research Org:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US)
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Country of Publication:
United States
Hydrothermal liquefaction; Hydrotreatment, Thermochemical conversions, biofuels, wastewater analysis