Influence of coal bottom ash additives on catalytic reforming of biomass pyrolysis gaseous tar and biochar/steam gasification reactivity

This work investigated the effect of CBA additives as bed material in gasification process on gaseous tar catalytic reforming characteristic and biochar/steam gasification reactivity adopting a lab-scale dual-stage fixed bed furnace and a thermogravimetric analyzer equipped with water vapor furnace. Results showed that CBA additive exhibited good catalytic performance for tar cracking and gas upgrading effect on the basis of larger specific surface area as well as higher content of metallic matters. Particularly, tar conversion efficiency and syngas acquired peaking at 92.39% and 594.3 mL/g adopting mixing biochar (PSC) with CBA at ratio of 1:15 (PSC-15CBA) as catalyst at reforming temperature of 900 degrees C, respectively, in which the main components of syngas are H2, CO and CH4. It is noted that PSC-nCBA exhibited higher deoxygenation extent and single-ring aromatics and aliphatic selectivity in tar, and the polycyclic aromatics selectivity evidently decreased. The CBA additive has a beneficial impact on the biochar/steam gasification reactivity. Interestingly, a relatively high proportion of CBA additive has a negative impact on promoting reactivity. Result from kinetics analysis that CBA additive had ability to reduce the activation energy of PSC gasification process.