Synergetic effects of biochar structure and AAEM species on reactivity of H₂O-activated biochar from cyclone air gasification

In order to investigate the synergetic effects of biochar structure and AAEM species on the reactivity of biochar, the H₂O activation of the cyclone air-gasified rice husk biochar was studied in the one-stage fluidized bed/fixed bed reactor. The details in the transformation of biochar structures and the properties of AAEM species were analyzed by FTIR, Raman and ICP–AES, respectively. The specific reactivity of biochar was determined in a thermogravimetric analyzer. The results indicated that those most marked synergetic effects of biochar structure and AAEM species on the H₂O-activated reactivity of biochar were observed in the temperature range from 750 °C to 850 °C. During the H₂O-activation reaction, the biochar reactivity would be improved due to the increase of surface oxygen-containing functional groups (i.e., R–OH and –COO) and small aromatic ring structures in biochar catalyzed by the AAEM species. The improvement in the reactivity of air-gasified biochar by the H₂O-activation is mainly in the initial carbon conversion (<15%) at 800 °C.