Process for recovering sugars from a pretreatment stream of lignocellulosic biomass

A process for the soaking of lignocellulosic biomass, comprising the steps of

• A) introducing a lignocellulosic biomass feedstock into a first soaking zone,
• B) soaking the lignocellulosic biomass feedstock in the presence of a liquid or vapor of the liquid for a first time and a first temperature correlating to a first severity of the soaking conditions creating a first liquid comprised of at least one compound selected from the group consisting of acetic acid, glucose, xylose and soluble oligomers thereof,
• C) separating at least a portion of the first liquid comprised of the at least one compound selected from the group consisting of acetic acid, glucose, xylose and soluble oligomers thereof from the biomass of the first soaking,
• D) introducing the biomass of the first soaking zone into a second soaking zone in the presence of a liquid for a second time and a second temperature correlating to a second severity of the soaking conditions creating a second liquid comprised of at least one compound selected from the group consisting of acetic acid, glucose, xylose and soluble oligomers thereof wherein the second severity is greater than first severity, and
• E) separating at least a portion of the second free liquid comprised of the at least one compound selected from the group consisting of acetic acid, glucose, xylose and soluble oligomers thereof from the biomass of the second soaking