Hydrothermal Depolymerization of Biorefinery Lignin-Rich Streams: Influence of Reaction Conditions and Catalytic Additives on the Organic Monomers Yields in Biocrude and Aqueous Phase

Stefano Dell’Orco, Edoardo Miliotti, Giulia Lotti, Andrea Maria Rizzo, Luca Rosi and David Chiaramonti
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Stefano Dell’Orco: RE-CORD, Viale Kennedy 182, Scarperia e San Piero, 50038 Florence, Italy
Edoardo Miliotti: RE-CORD, Viale Kennedy 182, Scarperia e San Piero, 50038 Florence, Italy
Giulia Lotti: RE-CORD, Viale Kennedy 182, Scarperia e San Piero, 50038 Florence, Italy
Andrea Maria Rizzo: RE-CORD, Viale Kennedy 182, Scarperia e San Piero, 50038 Florence, Italy
Luca Rosi: RE-CORD, Viale Kennedy 182, Scarperia e San Piero, 50038 Florence, Italy
David Chiaramonti: RE-CORD, Viale Kennedy 182, Scarperia e San Piero, 50038 Florence, Italy

Energies, 2020, vol. 13, issue 5, 1-22

Abstract: Hydrothermal depolymerization of lignin-rich streams (LRS) from lignocellulosic ethanol was successfully carried out in a lab-scale batch reactors unit. A partial depolymerization into oligomers and monomers was achieved using subcritical water as reaction medium. The influence of temperature (300–350–370 °C) and time (5–10 minutes) was investigated to identify the optimal condition on the monomers yields in the lighter biocrude (BC1) and aqueous phase (AP) fractions, focusing on specific phenolic classes as well as carboxylic acids and alcohols. The effect of base catalyzed reactions (2–4 wt. % of KOH) was compared to the control tests as well as to acid-catalyzed reactions obtained with a biphasic medium of supercritical carbon dioxide (sCO 2 ) and subcritical water. KOH addition resulted in enhanced overall depolymerization without showing a strong influence on the phenolic generation, whereas sCO 2 demonstrated higher phenolic selectivity even though no effect was observed on the overall products mass yields. In conclusion, a comparison between two different biocrude collection procedures was carried out in order to understand how the selected chemical extraction mode influences the distribution of compounds between BC1 and AP.

Keywords: Biorefinery; hydrothermal liquefaction; lignin stream recovery; lignin depolymerization; catalyzed liquefaction; supercritical carbon dioxide; biocrude and aqueous phase characterization; liquefaction conditions; biocrude solvent extraction (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2020
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (2)

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