Production of biofuel precursors and value-added chemicals from hydrolysates resulting from hydrothermal processing of biomass: A review

Highlights: • Hydrolysates can be produced from biomass under sub- and supercritical conditions. • Synthetic routes for platform chemicals from hydrolysates are reviewed. • Hydrolysate conversions to platform chemicals and bioenergy moities are promising. • Research avenues for techno-economically feasible biosystems are proposed. -- Abstract: The hydrothermal pretreatment route is gaining research interest as a potentially green method for deconstructing lignocellusic biomass. Based on the relevant literature, the conversion of biomass into platform chemicals or energy carriers through hydrothermal processes has been found to be advantageous by reason of enhanced process performance, while being environmentally friendly and technologically innovative. In this review, an assessment has been made of recent research findings and reservations in regard to the synthesis of subcritical and supercritical hydrolysates and the production of platform chemicals namely ethanol, butanol, furfural, hydroxymethylfurfural, lactic acid, levulinic acid and its derivatives, succinic acid, sorbitol, and xylitol. This review also proposes a number of future research-oriented directions to harness the findings of primary research-oriented efforts for developing technically and economically feasible large-scale systems.