Investigation into biochar supported Fe-Mo carbides catalysts for efficient biomass gasification tar cracking

Advanced and low-cost catalytic materials (catalysts) play an enabling role in tar cracking for biomass gasification technology and contributing to reducing CO2 emissions. Herein, a biochar supported Fe-Mo carbides catalyst was synthesized by impregnation method combined with in-situ carbothermal reduction from abundant biomass raw materials. The catalytic performance over a series of Fe-Mo carbides catalysts was examined by a two-stage pyrolysis-catalysis reactor. The addition of Mo species promoted the carbon solvation on the surface of Fe particles to form Fe3C active sites which further etching the carbon support with an abundant mesoporous structure. Fe-Mo0.5@C catalyst demonstrated a high tar cracking efficiency of 91.05% and remained at 84.77% after 5 cycles. The tar conversion pathways were summarized based on gas yields and components of residual tar. The Fe3C-Mo2C active sites contributed to the cleavage of oxygen-containing macromolecules to generate light aromatic hydrocarbons and phenolic substances with stable structures. Besides, the carbothermal reduction regeneration was carried out under N2 atmosphere at 800 °C to obtain regenerated catalysts to overcome coke deposition and metal oxidation, which recovered the tar conversion efficiency to 90.41%. The tar catalytic cracking mechanism over biochar supported Fe-Mo carbides catalyst was also first proposed. The results showed that biochar supported Fe-Mo carbides catalyst is a promising catalyst for efficient biomass tar catalytic cracking.