Patent ID: 8394611

Claim:
A process for treating structural carbohydrates in lignocellulosic biomass comprising: reacting the lignocellulosic biomass with added water and a heated concentrated aqueous ammonium hydroxide solution having a concentration from greater than 30% up to about 100% by weight ammonia in a closed vessel at an elevated temperature and pressure; simultaneously with the reacting step, manipulating the temperature, a mass ratio of ammonia to a dry lignocellulosic biomass and a mass ratio of the added water to the dry lignocellulosic biomass to produce treated lignocellulosic biomass having increased digestibility and/or increased accessibility of the structural carbohydrates; rapidly releasing the pressure in the vessel; recovering at least some of the ammonia and ammonium hydroxide from the treated lignocellulosic biomass and the ammonium hydroxide solution, wherein the ammonia is stripped with steam for recycling; and optionally further processing the treated lignocellulosic biomass via enzymes, microbial conversion or animal digestive process, wherein monosaccharide yield from the structural carbohydrates in the treated lignocellulosic biomass is increased as compared with a treatment process which does not include adding water in combination with concentrated aqueous ammonium hydroxide solution.