Potassium catalytic hydrogen production in sorption enhanced gasification of biomass with steam

• H2 yield was promoted by adding K2CO3 or CH3COOK but inhibited by adding KCl.
• K2CO3 showed different catalytic activity from CH3COOK from 600 °C to 700 °C.
• Carbon conversion in SEG process was enhanced by adding K2CO3 or CH3COOK.
• The results can be used to select a proper catalyst in SEG process.

Sorption enhanced gasification (SEG) of biomass with steam was investigated in a fixed-bed reactor to elucidate the effects of temperature, catalyst type and loading on hydrogen production. K2CO3, CH3COOK and KCl were chosen as potassium catalyst precursors to improve carbon conversion efficiency in gasification process. It was indicated that from 600 °C to 700 °C, the addition of K2CO3 or CH3COOK catalyzed the gasification for hydrogen production, and hydrogen yield and carbon conversion increased with increasing catalyst loadings of K2CO3 or CH3COOK. However, the hydrogen yield and carbon conversion decreased as the amount of KCl was increased due to inhibition of KCl on gasification. The maximum carbon conversion efficiency (88.0%) was obtained at 700 °C corresponding to hydrogen yield of 73.0 vol.% when K2CO3 of 20 wt.% K loading was used. In particular, discrepant catalytic performance was observed between K2CO3 and CH3COOK at different temperatures and the corresponding mechanism was also discussed.