Hydrogen production from catalytic steam-gasification of biomass using char and char-supported iron catalysts

Char derived from the pyrolysis of carbon-based fuels, such as biomass and coal, has been widely used as a support material. In this study, biochar, coalchar, biochar-supported Fe (Fe/B) and coalchar-supported Fe (Fe/C) were prepared for tar cracking and H₂ enhancement during wood chips gasification. All experiments were conducted in a fluidized bed gasification system using steam as the gasification agent. The results revealed that the effectiveness of each catalyst in removing tar is ranked as follows: biochar < coalchar < Fe/B < Fe/C. The highest H₂ content (49.2 vol%) was also obtained at 800 ^°C and in the presence of 6 wt% Fe/C as catalyst. Tar cracking improved significantly with increasing Fe content from 0 to 6.0 wt%, but showed little further improvement beyond 6.0 wt% Fe content. The results indicated that adding steam had minimal effect on the tar content in the gas produced from the gasification of wood chips using the Fe/C catalyst. However, raising the gasifier temperature from 700 to 850 ^°C led to a significant reduction in tar yield. This reduction is attributed to the promotion of cracking and reforming reactions during the gasification process. This work showed that the char composition significantly influences its catalytic performance regarding tar reduction and H₂ enhancement.