Lignocellulosic biomass hydrolysis without enzymes or acid catalysts

A process for the hydrolysis of C5 and C6 sugars present in a ligno-cellulosic biomass feed stream wherein the process comprises the steps of:

• A. pretreating the ligno-cellulosic biomass feed stream to create a pretreated solid ligno-cellulosic biomass stream comprising water insoluble C6 sugars and a liquid biomass solution comprising water soluble C5 sugars,
• B. creating an acidic stream from the liquid biomass solution by increasing the number of H+ ions in the liquid biomass solution by an amount sufficient so that the pH of the acidic stream is at least 0.5 pH units less than the pH of the liquid biomass solution prior to the addition of the H+ ions, wherein less than 90% of the total amount of H+ ions added to the acidic stream are derived from an acid or acids,
• C. combining at least a portion of the acidic stream comprising water soluble C5 sugars with at least a portion of the water insoluble C6 sugars to create a mixture, and
• D. hydrolyzing at least one of the C5 and C6 sugars of the mixture by increasing the temperature of the mixture to a hydrolysis temperature greater than 80° C. for a hydrolysis time greater than 0.5 minutes.