Abstract
Lignin depolymerization could provide an attractive renewable aromatic feedstock for the chemical industry. Past studies have suggested that lignin structural features such as ether content are correlated to lignin's upgradeability. An obstacle to the development of a conclusive causal relationship between lignin structure and upgradeability has been the difficulty to quantitatively measure lignin structural features. Here, we demonstrated that a modified HSQC-NMR method known as HSQC0 can accurately quantify lignin functionalities in extracted lignin using several synthetic polymer models. We then prepared a range of isolated lignin samples with a wide range of ether contents (6-46%). By using a simple ether cleavage model, we were able to predict final depolymerization yields very accurately (<4% error), conclusively demonstrating the direct causal relationship between ether content and lignin activity. The accuracy of this model suggests that, unlike in native lignin, ether linkages no longer appear to be randomly distributed in isolated lignin.
| Original language | English |
|---|---|
| Pages (from-to) | 8135-8142 |
| Number of pages | 8 |
| Journal | Chemical Science |
| Volume | 10 |
| Issue number | 35 |
| DOIs | |
| Publication status | Published - 2019 |
| MoE publication type | A1 Journal article-refereed |
Funding
This work was supported by the Swiss National Science Foundation through grants PYAPP2-154281 and CRSII5-180258, by the Swiss Competence Center for Energy Research: Biomass for a Swiss Energy Future through the Swiss Commission for Technology and Innovation grant KTI.2014.0116, and by EPFL. The authors thank J. Ralph (UW Madison) for the suggestion to explore the use of HSQC0, J. Morisod (EPFL) for his help with gel permeation chromatography, A. Bornet for his help performing NMR experiments and W. Lan (EPFL) for providing initial acidolysis lignin samples and for NMR suggestions. Finally, we thank M. Studer from Bern University of Applied Sciences (Switzerland) for providing various wood samples. This work was supported by the Swiss National Science Foundation through grants PYAPP2_154281 and CRSII5_180258, by the Swiss Competence Center for Energy Research: Biomass for a Swiss Energy Future through the Swiss Commission for Technology and Innovation grant KTI.2014.0116, and by EPFL. The authors thank J. Ralph (UW Madison) for the suggestion to explore the use of HSQC0, J. Morisod (EPFL) for his help with gel permeation chromatography, A. Bornet for his help performing NMR experiments and W. Lan (EPFL) for providing initial acidolysis lignin samples and for NMR suggestions. Finally, we thank M. Studer from Bern University of Applied Sciences (Switzerland) for providing various wood samples.