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Monitoring Molecular Weight Changes during Technical Lignin Depolymerization by Operando Attenuated Total Reflectance Infrared Spectroscopy and Chemometrics
Author(s) -
Khalili Khaled N. M.,
Peinder Peter,
Donkers Jacqueline,
Gosselink Richard J. A.,
Bruijnincx Pieter C. A.,
Weckhuysen Bert M.
Publication year - 2021
Publication title -
chemsuschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.412
H-Index - 157
eISSN - 1864-564X
pISSN - 1864-5631
DOI - 10.1002/cssc.202101853
Subject(s) - depolymerization , lignin , attenuated total reflection , dispersity , chemometrics , infrared spectroscopy , chemistry , spectroscopy , size exclusion chromatography , analytical chemistry (journal) , chemical engineering , organic chemistry , chromatography , physics , quantum mechanics , engineering , enzyme
Technical lignins are increasingly available at industrial scale, offering opportunities for valorization, such as by (partial) depolymerization. Any downstream lignin application requires careful tailoring of structural properties, such as molecular weight or functional group density, properties that are difficult to control or predict given the structure variability and recalcitrance of technical lignins. Online insight into changes in molecular weight ( M w ), to gauge the extent of lignin depolymerization and repolymerization, would be highly desired to improve such control, but cannot be readily provided by the standard ex‐situ techniques, such as size exclusion chromatography (SEC). Herein, operando attenuated total reflectance infrared (ATR‐IR) spectroscopy combined with chemometrics provided temporal changes in M w during lignin depolymerization with high resolution. More specifically, ex‐situ SEC‐derived M w and polydispersity data of kraft lignin subjected to aqueous phase reforming conditions could be well correlated with ATR‐IR spectra of the reaction mixture as a function of time. The developed method showed excellent regression results and relative error, comparable to the standard SEC method. The method developed has the potential to be translated to other lignin depolymerization processes.