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 N₂, CO₂ and H₂O 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 H₂O and CO₂ atmospheres. The evolution of char pore structures under H₂O and CO₂ was quite different. The formation of micropores was facilitated by CO₂, while mesopores and macropores were developed more in H₂O 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. CO₂ preferred to react with amorphous carbon, while the cross-linked carbon was more likely to be consumed during char gasification with H₂O.