Direct saccharification of lignocellulosic biomass by hydrolysis with formic acid solution

An effective hydrolysis method for recovering oligosaccharides directly from lignocellulosic biomass has been investigated. Formic acid was selected as a hydrolysis reagent, due to its high acidity in organic acids. The degrees of cellulose hydrolysis and lignin elution were determined by the combination of the reaction temperature and formic acid aqueous solution concentration. We successfully obtained approximately 47 wt% of oligosaccharides, keeping the minimum lignin elution at 150 degrees C and with 25 vol% formic acid aqueous solution concentration. Such a high yield of oligosaccharides was due to the relaxation of biomass structure. Furthermore, by diluting the formic acid aqueous solution concentration, or evaporating the solution, lignin can be separated from the oligosaccharides completely as deposits. Finally, two options for the efficient recovery of saccharides have been proposed.