Structural Changes of Lignin during OrganoCat Processing

Energy & Fuels, vol. 38, pp. 4192–4202

Abstract

High Resolution Image Download MS PowerPoint Slide The isolation of high-quality lignin from lignocellulose plays a pivotal role in the holistic use of biomass. Hence, modern approaches aim to avoid recondensation reactions of lignin during extraction and aim to maintain most of the native structure. This increases its solubility and the proportion of cleavable beta aryl linkages, which can be of advantage in the subsequent process chain. As the lignin structure varies greatly between different plant groups, understanding the effect of lignin structural features on processing and vice versa is a prerequisite for industrial application. In this study, a two-step process using concentrated phosphoric acid in a swelling step and then a biphasic fractionation process utilizing diluted phosphoric acid under mild conditions was used as a benchmark to extract lignin from 10 structurally and compositionally different plant materials. Pyrolysis-gas chromatography–mass spectrometry and 1 H– 13 C-heteronuclear single quantum correlation-nuclear magnetic resonance were used to identify the monomer unit composition and the linkage proportion of lignin before and after extraction and combined with size exclusion chromatography, wet chemical analysis of the biomass, and fractionation yields to identify correlations before and after processing. After processing, the relative beta aryl ether linkage content decreased greatly from 40–90 to 20–40 linkages per 100 monomer units. The molecular weight ( M w ) of extracted lignin was measured to be between 2000 and 6800 Da, indicating that the fractionation process produces relatively uniform lignin in these aspects from different plant sources. Nevertheless, lignin structure properties such as beta aryl and resinol linkages showed an influence on delignification and lignin size.

Authors 8

1. Leonie Schoofs Aachen

   Forschungszentrum Jülich · RWTH Aachen University

   Affiliation as printed

   Institute for Bio and Geo Sciences 2, Plant Sciences, Forschungszentrum Jülich GmbH, Wilhelm-Johnen-Straße, 52428 Jülich, Germany

   RWTH Aachen University, 52074 Aachen, Germany

2. Björn Thiele

   Forschungszentrum Jülich

   Affiliation as printed

   Institute for Bio and Geo Sciences 2, Plant Sciences, Forschungszentrum Jülich GmbH, Wilhelm-Johnen-Straße, 52428 Jülich, Germany

   Institute for Bio and Geo Sciences 3, Agrosphere, Forschungszentrum Jülich GmbH, Wilhelm-Johnen-Straße, 52428 Jülich, Germany

3. Josia Tonn Aachen AVT—Fluid Process Engineering

   Forschungszentrum Jülich · RWTH Aachen University

   Affiliation as printed

   AVT-Fluid Process Engineering, RWTH Aachen University, Forckenbeckstraße 51, 52074 Aachen, Germany

   Bioeconomy Science Center (BioSC), Forschungszentrum Jülich GmbH, 52425 Jülich, Germany

4. Tim Langletz Aachen Institute of Inorganic Chemistry

   Forschungszentrum Jülich · RWTH Aachen University

   Affiliation as printed

   Bioeconomy Science Center (BioSC), Forschungszentrum Jülich GmbH, 52425 Jülich, Germany

   Institute of Inorganic Chemistry, RWTH Aachen University, Landoltweg 1a, 52074 Aachen, Germany

5. Sonja Herres‐Pawlis Aachen Institute of Inorganic Chemistry

   Forschungszentrum Jülich · RWTH Aachen University

   Affiliation as printed

   Bioeconomy Science Center (BioSC), Forschungszentrum Jülich GmbH, 52425 Jülich, Germany

   Institute of Inorganic Chemistry, RWTH Aachen University, Landoltweg 1a, 52074 Aachen, Germany

6. Andreas Jupke Aachen AVT—Fluid Process Engineering

   Forschungszentrum Jülich · RWTH Aachen University

   Affiliation as printed

   AVT-Fluid Process Engineering, RWTH Aachen University, Forckenbeckstraße 51, 52074 Aachen, Germany

   Bioeconomy Science Center (BioSC), Forschungszentrum Jülich GmbH, 52425 Jülich, Germany

   Institute for Bio and Geo Sciences 2, Plant Sciences, Forschungszentrum Jülich GmbH, Wilhelm-Johnen-Straße, 52428 Jülich, Germany

7. Philipp Michael Grande corresponding

   Forschungszentrum Jülich

   Affiliation as printed

   Bioeconomy Science Center (BioSC), Forschungszentrum Jülich GmbH, 52425 Jülich, Germany

   Institute for Bio and Geo Sciences 2, Plant Sciences, Forschungszentrum Jülich GmbH, Wilhelm-Johnen-Straße, 52428 Jülich, Germany

8. Holger Klose corresponding Aachen

   Forschungszentrum Jülich · RWTH Aachen University

   Affiliation as printed

   Bioeconomy Science Center (BioSC), Forschungszentrum Jülich GmbH, 52425 Jülich, Germany

   Institute for Bio and Geo Sciences 2, Plant Sciences, Forschungszentrum Jülich GmbH, Wilhelm-Johnen-Straße, 52428 Jülich, Germany

   RWTH Aachen University, 52074 Aachen, Germany