Thermal stability of low and high Mw fractions of bio-oil derived from lignin conversion in subcritical water
Artikel i vetenskaplig tidskrift, 2017

The thermal stability of bio-oil influences its application in industry and is, therefore, a very important factor that must be taken into consideration. In this study, the stability of low and high molecular weight (Mw) fractions of bio-oil obtained from the hydrothermal liquefaction (HTL) of lignin in subcritical water was studied at an elevated temperature (80 °C) for a period of 1 h, 1 day and 1 week. The changes in molecular weight (gel permeation chromatography (GPC)) and chemical composition (gas chromatography–mass spectrometry (GC–MS) and 2D heteronuclear single quantum correlation (HSQC) NMR (18.8 T, DMSO-d6)) of low and high Mw fractions of the HTL bio-oil (i.e. light oil (LO) and heavy oil (HO)) were evaluated before and after ageing. It was found that only a slight formation of high Mw insoluble structures was obtained during ageing at elevated temperature for 1 week: 0.5% for the LO and 3.1% for the HO. These higher Mw moieties might be formed from different polymerisation/condensation reactions of the reactive compounds (i.e. anisoles, guaiacols, phenols, methylene (–CH2–) groups in phenolic dimers and xanthene). The high Mw insolubles in both the LO and the HO were analysed for structural composition using 2D HSQC NMR to obtain a better understanding of the changes in the composition of bio-oil fractions during the accelerated ageing process. In addition, a chemical shift database in DMSO-d6 was analysed for a subset of phenolic model compounds to simplify the interpretation of the 2D HSQC NMR spectra.

Subcritical water



Hydrothermal liquefaction




Huyen Nguyen Lyckeskog

Chalmers, Kemi och kemiteknik, Kemiteknik

Cecilia Mattsson

Chalmers, Kemi och kemiteknik, Kemiteknik

Lars Olausson


Sven-Ingvar Andersson

Chalmers, Kemi och kemiteknik, Kemiteknik

Lennart Vamling

Chalmers, Kemi och kemiteknik, Kemiteknik

Hans Theliander

Chalmers, Kemi och kemiteknik, Kemiteknik

Wallenberg Wood Science Center (WWSC)

Biomass Conversion and Biorefinery

2190-6815 (ISSN) 2190-6823 (eISSN)

Vol. 7 4 401-414





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