Mechanisms of catalytic reforming of biomass pyrolysis volatiles by Ce promoted Fe–Ni/biochar under N2 and steam atmosphere

In this work, the promotion mechanism of Ce as Fe and Ni catalyst promoter for the catalytic reforming of biomass pyrolysis volatiles was investigated. Fe–Ni–Ce/biochar catalysts were prepared and evaluated for their catalytic performance under N2 and steam atmospheres. The yield of Fe–Ni–Ce/biochar catalyzed syngas (H2+CO) increased from 224.36 mL/g to 1299.14 mL/g (800 °C) with the change of N2 to steam atmosphere. The addition of Ce can introduce a large number of oxygen vacancies to the catalyst, and the increase of oxygen vacancies reduces the reaction barrier of the tar, thus promoting the catalytic activity of the catalyst. In the N2 atmosphere, the electron transfer of Ce3+ ⇄ Ce4+ during catalytic process promotes the production of Fe2+ to ensure the catalytic activity of the catalyst. In the steam atmosphere, Ni will activate the active sites in a steam atmosphere in water molecules. The activated active sites increase the catalyst activity by cyclic reaction with the oxygen vacancies introduced by Ce, resulting in a higher catalytic capacity of Fe–Ni/biochar than Fe–Ce/biochar. To provide the theoretical basis for the preparation of efficient catalysts based on Fe and Ni.