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Licensed Unlicensed Requires Authentication Published by De Gruyter August 28, 2017

Optimizing Douglas-fir bark liquefaction in mixtures of glycerol and polyethylene glycol and KOH

  • Bruno Esteves ORCID logo EMAIL logo , Luísa Cruz-Lopes , José Ferreira , Idalina Domingos , Lina Nunes and Helena Pereira
From the journal Holzforschung


The outer bark of Douglas-fir (Pseudotsuga menziesii) has a significant amount of cork tissue that may be an important source of chemicals derived from its natural polymers, suberin, cellulose, hemicelluloses and lignin. The present work focuses on the polyalcohol liquefaction of Douglas-fir bark with glycerol and polyethylene glycol (PEG) in order to obtain a liquid that can be further processed to other chemicals and products. The results show that Pseudotsuga bark can be liquefied in a significant percentage in presence of alkali. The best liquefaction yield was obtained with 6% KOH as agents. Although the use of a cosolvent is favorable, good liquefaction yields can also be obtained by glycerol alone. Lower temperatures are favorable as they lead to acceptable liquefaction yields. FTIR-ATR studies showed that all the structural compounds of the bark were attacked and depolymerized. The process tested has a high potential for generation of value-added products from liquefied Douglas-fir bark.


This work is financed by national funds through FCT – Fundação para a Ciência e a Tecnologia, I.P., under the project UID/Multi/04016/2016. Furthermore, we would like to thank the Instituto Politécnico de Viseu and CI&DETS for their support. Centro de Estudos Florestais is a research unit funded by FCT (UID/AGR/00239/2013).


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Received: 2017-1-31
Accepted: 2017-7-24
Published Online: 2017-8-28
Published in Print: 2017-12-20

©2018 Walter de Gruyter GmbH, Berlin/Boston

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