Lignocellulosic biomass is a promising sustainable feedstock for the production of biofuels, biomaterials, and biospecialty chemicals. Unfortunately, the molecular level structure of biomass was poorly understood, due to its rigid and compact structure. The crystallinity of cellulose and its cross-linking with lignin rinders it particularly resilient to biodegradation. In this study, lignin was removed effectively by using earth abundant metal catalyst through catalytic depolymerization of lignin (CDL) process. The remaining carbohydrates was then subjected to structure study as well as further catalytic conversion. Dynamic Nuclear Polarization (DNP) - Enhanced Solid State NMR and XRD study on post CDL treated cellulose indicated that the CDL process was highly selective for the removal of lignin, while the structure of remaining carbohydrates remained intact. Comparison of post CDL treated cellulose and raw biomass revealled an increase in the crystallinity for the post CDL treated cellulose. Catalytic conversion of post CDL treated carbohydrates with iron chloride gave higher yields of platform chemicals (furfural and levulinic acid), compared with raw biomass. Enzymatic hydrolysis comparison were performed using Cellic™ Ctec2, which indicated that cellulose is largely inaccessible in raw biomass, due to the cross-linking with lignin. However, the enzymatic hydrolysis yields on post CDL treated cellulose imcreased significantly.

Atomic-level structure characterization of carbohydrate pre and post lignin treatment by dynamic nuclear polarization: Enhanced solid state NMR

254th National Meeting (2017)

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