Chemical pretreatment is an essential step for the conversion of lignocellulosic biomass into fermentable sugars using enzymes. An effective pretreatment method with minimal use of water and chemical has previously been developed, termed as low moisture anhydrous ammonia (LMAA). This process comprises of two steps such as ammoniation followed by pretreatment. In this two-stage process, corn stover with approximately 50% moisture content was firstly contacted with anhydrous ammonia under mild reaction conditions with no additional pressure and temperature control, which is the ammoniation step. In the following step, a simple pretreatment step at moderately elevated temperatures (60–150°C) for 24–120 h was followed. In particular, this process requires no washing step which requires considerable energy input for evaporation and recovery of water and chemicals after pretreatment. The first part of this method is the ammoniation step; corn stover with approximately 50% moisture was contacted with anhydrous ammonia in a batch reactor under mild reaction conditions without additional heating. After the ammoniation stage, a simple pretreatment step was conducted using closed container/bottle at elevated temperatures (60-150oC) for 72-144 h. After the completion of the pretreatment step, enzymatic saccharification of pretreated solid can be directly applied without washing step.
In this study, it was found out that LMAA pretreatment have substantially enhanced the enzymatic saccharification yields compared to that of the untreated corn stover. It was indicated that pretreatment conditions such as temperature, time and residual ammonia had a relationship with improved enzymatic saccharification yields.