Effects of gaseous agents on the evolution of char physical and chemical structures during biomass gasification.

Bio-char samples were prepared from gasification of corn straw under N, CO and HO conditions, and systematically characterized to reveal the effects of gaseous agents on the evolution of char structural features during the gasification process. The results showed that the increase of reacting temperature had positive effects on the gasification of char in both HO and CO atmospheres. The evolution of char pore structures under HO and CO was quite different. The formation of micropores was facilitated by CO, while mesopores and macropores were developed more in HO condition. Besides, char structures obtained at 800 °C were more ordered than those obtained at 600 °C. Compared with the longitudinal merging, the aromatic layers preferred to grow laterally. Moreover, the mechanisms of gasification between char and gaseous agents were different. CO preferred to react with amorphous carbon, while the cross-linked carbon was more likely to be consumed during char gasification with HO.