NMR Characterization of Lignin

Currently, lignin is a major component of lignocellulosic biomass and an underutilized feedstock in the growing pulping and biorefinery industries. Structural characterization of lignin is important not only for revealing the inherent structure of lignin in different feedstocks but also for structural characterization and chemical reactivity determination of lignin isolated from different industrial and pretreatment processes. As one of the most promising diagnostic tools, NMR (nuclear magnetic resonance spectroscopy) provides unambiguous evidence for specific structures as well as quantitative structural information. In short, the main objective of this chapter is to introduce the application of NMR technique ( 1 H-NMR, 13 C-NMR, 2D-HSQC NMR, 31 P-NMR, 19 F NMR, and in-situ lignin characterization) in the characterizing the structural and chemical activity of lignin from different sources, such as native lignin, biorefinery lignin, and industrial lignin fractions, aiming to extend the lignin valorization and improve the techno-economics of applications of different lignin fractions in current biorefinery industries.