Abstract
Current lignin fractionation methods use harsh conditions that alter the native lignin structure, resulting in a recalcitrant material which is undesired for downstream processing. Milder fractionation processes allow for the isolation of lignins that are high in beta-aryl ether (beta-O-4) content, however, at reduced extraction efficiency. The development of improved lignin extraction methods using mild conditions is therefore desired. For this reason, a flow-through setup for mild ethanosolv extraction (120 degrees C) was developed. The influence of acid concentration, ethanol/water ratio, and the use of other linear alcohol co-solvents on the delignification efficiency and the beta-O-4 content were evaluated. With walnut shells as model feedstock, extraction efficiencies of over 55% were achieved, yielding lignin with a good structural quality in terms of beta-O-4 linking motifs (typically over 60 per 100 aromatic units). For example, lignin containing 66 beta-O-4 linking motifs was obtained with an 80:20 n-propanol/water ratio, 0.18 M H2SO4 with overall a good extraction efficiency of 57% after 5 h. The majority of the lignin was extracted in the first 2 hours and this lignin showed the best structural quality. Compared to batch extractions, both higher lignin extraction efficiency and higher beta-O-4 content were obtained using the flow setup.
Original language | English |
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Article number | 1913 |
Number of pages | 17 |
Journal | Polymers |
Volume | 11 |
Issue number | 12 |
DOIs | |
Publication status | Published - Dec-2019 |
Keywords
- biomass
- lignin
- flow-through setup
- organosolv extraction
- high beta-O-4 content
- REDUCTIVE CATALYTIC FRACTIONATION
- PRIMARY ALCOHOL OXIDATION
- FLOWTHROUGH PRETREATMENT
- BIOMASS
- ACID
- DEPOLYMERIZATION
- LIGNOCELLULOSE
- OPTIMIZATION
- VALORIZATION
- SOLVOLYSIS