Research paperSmall-scale low-moisture anhydrous ammonia (LMAA) pretreatment of corn stover

•The glucan digestibility of corn stover using low-moisture anhydrous ammonia (LMAA) pretreatment method has been investigated.•No significant reduction of the carbohydrates, such as glucan and xylan, was observed after the LMAA pretreatment process.•The highest glucan digestibility result was 71.6% of the theoretical.•Comparing with the small-scale experiment, the optimal conditions (72 h and 75 °C) didn't have a large shift; in other words, it remained relatively stable.

With many economic benefits, corn-based ethanol has been widely used in recent years. Cellulosic ethanol, however, require pretreatment to break down lingo-cellulosic structures prior to fermentation. Among all the pretreatment reagents that have been used, ammonia has proven to be one of the most effective, because it can readily delignify, swell, and preserve the polysaccharides. The purpose of this study was to determine optimal conditions (i.e. highest glucose yield) using the low-moisture anhydrous ammonia (LMAA) pretreatment process. In this experiment, corn stover was prepared with different moisture contents (20% w.b., 50% w.b., 80% w.b.) and particle sizes (9-30 mesh, 30-144 mesh). Corn stover was ammoniated for 30 min. Ammoniated corn stover was then subjected to different incubation times (24 h, 75 h, and 144 h) under different temperatures (20 °C, 70 °C, 120 °C). After that, compositional analyses, including moisture content, ash content, carbohydrates, and lignin content, were conducted. Enzymatic digestibility tests were also conducted. Results from this study will be used to improve the efficiency of pretreatment processing.