Catalytic Conversion of Structural Carbohydrates and Lignin to Chemicals

Lignocellulose and chitin are the two most abundant renewable sources of organic carbon available as alternative for chemical and fuel synthesis. Catalytic conversion of these composite polymers to monomers is a multifaceted challenge. Lignocellulose and chitin are inherently unreactive toward chemical attacks as they serve the function of structural materials in plants and animals. A combination of pretreatment and catalytic reaction is necessary to convert these materials into useful small molecules. These upstream reactions involving depolymerization of polymers are the roadblock for realizing future chemicals production based on biomass. In this chapter, we first discuss the pretreatment technologies currently available for lignocellulose and their relevance for catalytic conversion. Catalytic pathways for depolymerization of cellulose, hemicellulose, and lignin are then discussed, highlighting important reactions and mechanism. An analogy is derived between mechanism of cellulose hydrolysis using enzymes and heterogeneous carbon catalysts containing acidic functional groups. Finally, the use of chitin as a renewable carbon source is discussed. The chemical structure of chitin is described along with its origin from crab shells and availability. Recent advances in conversion of chitin to N-acetylglucosamine and its derivatives are described.