Pretreatment and Fractionation of Corn Stover Using Low Moisture Anhydrous Ammonia (LMAA)

An effective pretreatment method with minimal use of water and chemical has previously been developed, termed as low moisture anhydrous ammonia (LMAA). In brief, corn stover with ~50% moisture was contacted with anhydrous ammonia in a batch reactor under mild reaction conditions. After the aforementioned ammoniation step, a simple pretreatment step at moderate temperatures (60–90°C) for 72–120 h was followed. This two-stage pretreatment without an additional washing step enhanced enzymatic saccharification and fermentation yields, significantly. Corn stover, lignocellulosic biomass, has been considered as a valuable and abundant source of sugars and hydrocarbons if near complete fractionation can be achieved in the biorefinery facility. In this study, corn stover was treated using anhydrous ammonia by LMAA and a fractionation process of pretreated biomass was investigated to recover both sugars and lignin. After enzymatic processing of corn stover using both cellulase and hemicellulose, solid residue contains mostly lignin, which can be used for production of value-added product. Samples were subjected to the enzymatic digestibility test and fermentation test using simultaneous saccharification and fermentation (SSF). This reports the various effects of treatment pertinent to sugar recovery, chemical compositional changes, improved enzymatic digestibility and fermentability.