Volume 13, Issue 17 p. 4468-4477
Full Paper

Lignin-First Fractionation of Softwood Lignocellulose Using a Mild Dimethyl Carbonate and Ethylene Glycol Organosolv Process

Alessandra De Santi

Alessandra De Santi

Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, Groningen, The Netherlands

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Dr. Maxim V. Galkin

Dr. Maxim V. Galkin

Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, Groningen, The Netherlands

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Dr. Ciaran W. Lahive

Dr. Ciaran W. Lahive

Department of Chemical Engineering (ENTEG), University of Groningen, Nijenborgh 4, Groningen, The Netherlands

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Dr. Peter J. Deuss

Dr. Peter J. Deuss

Department of Chemical Engineering (ENTEG), University of Groningen, Nijenborgh 4, Groningen, The Netherlands

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Prof. Dr. Katalin Barta

Corresponding Author

Prof. Dr. Katalin Barta

Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, Groningen, The Netherlands

Department of Chemistry, Organic and Bioorganic Chemistry, University of Graz, Heinrichstrasse 28/II, 8010 Graz, Austria

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First published: 26 February 2020
Citations: 65

Graphical Abstract

A walk on the mild side: A mild lignin-first fractionation process using sulfuric acid as a catalyst and ethylene glycol as a stabilization agent in dimethyl carbonate was developed to produce a single monophenolic product and cellulose to yield 85 % glucose upon enzymatic hydrolysis from pine lignocellulose.

Abstract

A mild lignin-first acidolysis process (140 °C, 40 min) was developed using the benign solvent dimethyl carbonate (DMC) and ethylene glycol (EG) as a stabilization agent/solvent to produce a high yield of aromatic monophenols directly from softwood lignocellulose (pine, spruce, cedar, and Douglas fir) with a depolymerization efficiency of 77–98 %. Under the optimized conditions (140 °C, 40 min, 400 wt % EG and 2 wt % H2SO4 to pinewood), up to 9 wt % of the aromatic monophenol was produced, reaching a degree of delignification in pinewood of 77 %. Cellulose was also preserved, as evidenced by a 85 % glucose yield after enzymatic digestion. An in-depth analysis of the depolymerization oil was conducted by using GC-MS, HPLC, 2 D-NMR, and size-exclusion chromatography, which provided structural insights into lignin-derived dimers and oligomers and the composition of the sugars and derived molecules. Mass balance evaluation was performed.

Conflict of interest

The authors declare no conflict of interest.