Green and Sustainable Biomass Processing for Fuels and Chemicals

Among different carbon sources, biomass is the most abundant organic carbon source available for producing renewable bio-oils and the value-added chemicals. Hydrothermal liquefaction (HTL) is a green method for sustainable transformation of dry and wet waste biomass to bio-oils and chemical products that are potentially applicable as raw materials in chemical industries. Both sub- and supercritical water possess interesting physicochemical properties, capable of dissolving a variety of waste materials for chemical synthesis and production of valuable liquid, gaseous and solid products. Under supercritical conditions, reactions like supercritical water gasification and supercritical water oxidation produce hydrolyzed and depolymerized products useful as synthetic intermediates in chemical industries. This chapter describes how hydrothermal conversion of waste biomass of different types containing both sugar and non-sugar derivatives leads to renewable biofuels and commodity chemicals by abiding green chemistry principles. Further, valorization of aqueous phase, obtained during hydrothermal processing, has also been discussed, including the chemical composition, reuse and applications for the chemical-enhanced recoveries. Therefore, the hydrothermal conversion of non-renewable waste biomass including agricultural waste, forest residue and organic (food) waste into valuable chemicals products can generate the wide opportunities for the development of sustainable chemical industries.