Beech (Fagus Sylvatica) milled-wood lignin was used as a model substrate in a study of lignin-catalyzed liquefaction in the presence of p-toluene sulfonic acid monohydrate (PTSA) or sulphuric acid as the catalysts. The structural changes that lignin undergoes during the treatment were studied by NMR spectroscopy, FTIR, size-exclusion chromatography, and high-performance liquid chromatography. For the sulphuric acid-catalyzed liquefaction, it was shown that the greater hydronium ion concentration in the reaction mixture induced formation of more condensed structures compared to the ones obtained after PTSA-catalyzed liquefaction. In addition, lignin during the PTSA-catalyzed liquefaction suffered degradation and was functionalized by the ethylene glycol. Gradual introduction of the ethylene glycol moieties into the lignin structure formed a condensed lignin-based polymeric material with predominant aromatic hydroxyl groups. HPLC and NMR analysis of the liquefied lignin with low-molecular mass fraction confirmed the presence of lignin monomers and further conversion of initially identified products into the aliphatic, aromatic (syringyl- and guaiacyl-based) esters and acids. © 2012 Copyright Taylor and Francis Group, LLC.
|Data di pubblicazione:||2012|
|Titolo:||Lignin structural changes during liquefaction in acidified ethylene glycol|
|Rivista:||JOURNAL OF WOOD CHEMISTRY AND TECHNOLOGY|
|Digital Object Identifier (DOI):||http://dx.doi.org/10.1080/02773813.2012.698690|
|Appare nelle tipologie:||2.1 Articolo su rivista |