Data for "Operando monitoring of delignification processes using 2D 1H-13C HSQC NMR"

The design of effective lignin extraction and depolymerization processes has long been hindered by a lack of understanding of biomass matrix and lignin architecture, especially during its transformation. Our current understanding of lignin valorization processes largely relies on the use of ex situ analysis techniques focusing on end-products, rather than operando monitoring of reaction mechanism and temporal structural changes. Here, we used a custom heteronuclear single quantum correlation (HSQC) NMR procedure to monitor molecular-specific temporal changes in lignin functionalities during extraction and depolymerization. Preferred condensation on guaiacol rings was observed in alkaline conditions. We also highlighted faster cleavage of phenolic β—O—4 linkages in acidic conditions and revealed the role of the acid counter-ion in this mechanism. Similarly, we were able to explore the important roles of methanol both in solvolysis and in functionalizing lignin during Reductive Catalytic Fractionation (RCF) of biomass. Overall, operando NMR HSQC spectra provide time-resolved information on biomass extraction processes in liquid phase and allowed us to identify important intermediates that are difficult to detect with ex situ characterization.