Plant Biomass Characterization: Application of Solution- and Solid-State NMR Spectroscopy

The conversion of plant biomass to biofuels is considered a promising alternative to reliance on diminishing supplies of fossil fuels, providing a sustainable option for fuels production in an environmentally compatible manner. However, the effective conversion of lignocellulosic biomass to liquid biofuels usually suffers from intrinsic recalcitrance of biomass due to the complicated structure of plant cell walls in which the major structural constituents are cellulose, hemicellulose, and lignin. Considerable efforts have been devoted to developing pretreatment technologies that alter the structure of biomass to reduce recalcitrance. This chapter focuses on application of nuclear magnetic resonance (NMR) spectroscopy for biomass characterization with an emphasis on lignin and cellulose constituents of biomass. One- and two-dimensional-solution NMR is discussed for lignin structure characterization, while solid-state cross-polarization/magic angle spinning (CP/MAS) 13C NMR is focused on analysis of the crystallinity and ultrastructure of cellulose. The solution and solid-state NMR techniques presented in this chapter offer effective tools for analysis of lignin and cellulose in biological and chemical conversion of biomass to fuels and chemicals.