CHAPTER 3: Ionic liquid pretreatment of lignocellulosic biomass for biofuels and chemicals

This chapter focuses on the recent development of biomass pre-treatment using ionic liquids (ILs). Lignocellulosic biomass, such as wood, grass, and agricultural residues, are a promising alternative source for the production of renewable fuels and chemicals. Because of the inherent recalcitrance, pre-treatment of lignocellulosic biomass is essential to improve the bioconversion process. Different physical, chemical and physicochemical pre-treatments are reported in literature and each process has its own advantages and disadvantages. Ionic liquids (ILs) are promising solvents for biomass pre-treatment as some ILs are capable of completely solubilizing lignocellulosic biomass and the biomass can then be regenerated upon addition of a suitable anti-solvent. Dissolution in IL drives structural changes in the regenerated biomass, making it easier to hydrolyse. The chapter starts with an overview of biomass and different emerging pre-treatment technologies, with an emphasis on IL-based pre-treatment technology. This section covers the history along with a concise literature review of different IL-based pre-treatment processes. The second section is devoted to IL pre-treatment chemistry and cellulose-IL interaction, with a short discussion of lignin and its prospects for the production of renewable platform chemicals. The last part of this chapter outlines the challenges and opportunities of the emerging IL pre-treatment technology in a biorefinery concept and provides concluding remarks on the outlook for the biorefinery.