Thermal stability of low and high Mw fractions of bio-oil derived from lignin conversion in subcritical water
Journal article, 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

Lignin

Stability

Hydrothermal liquefaction

Bio-oil

Storage

Author

Huyen Nguyen Lyckeskog

Chalmers, Chemistry and Chemical Engineering, Chemical Technology

Cecilia Mattsson

Chalmers, Chemistry and Chemical Engineering, Chemical Technology

Lars Olausson

Valmet

Sven-Ingvar Andersson

Chalmers, Chemistry and Chemical Engineering, Chemical Technology

Lennart Vamling

Chalmers, Chemistry and Chemical Engineering, Chemical Technology

Hans Theliander

Chalmers, Chemistry and Chemical Engineering, Chemical Technology

Wallenberg Wood Science Center (WWSC)

Biomass Conversion and Biorefinery

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

Vol. 7 4 401-414

Subject Categories

Chemical Engineering

DOI

10.1007/s13399-016-0228-4

More information

Latest update

2/21/2023