AbstractThe objective of this study was to investigate the anaerobic digestion performance and mechanism of corn stover pretreated with ammonia at three ammonia concentrations (2, 4, and 6%) and four moisture contents (30, 50, 70, and 90%). The physical and chemical structures as well as the changes in its chemical compositions of ammonia-pretreated corn stover were analyzed to understand its biogas production performance. The results showed that ammonia pretreatment could effectively improve the anaerobic digestion performance of corn stover and that the optimal biogas production performance was achieved with 4% ammonia and 70% moisture content. The maximum biogas yield reached 427.1 mL/gVS. The conversion rates of cellulose and hemicellulose were 80.60 and 68.5%, respectively, which is about 30 and 26% higher than those of the untreated corn stover, respectively. The composition and structure analyses showed that ammoniation pretreatment could rupture chemical bonds such as ester and ether bonds in the lignocellulose, partially degrade aliphatic and carbohydrate compounds, and bring anaerobes into sufficient contact with corn stover material, therefore helping to increase biogas yield.