Hydrogen production by catalytic reforming using Fe-Zn modified chitin biochar

To investigate high-efficiency pyrolysis-derived biochar catalysts for hydrogen production, three biochar catalysts were prepared by one-step impregnation-carbonization method using chitin（a naturally nitrogen-rich raw material）as precursor, and Fe and Zn as metal loading sources．Three catalysts included chitin biochar（T₁ catalyst）, iron nitrate-supported biochar（T₂ catalyst）, and Fe-Zn-supported biochar（T₃ catalyst）．Rice husk were used as biomass feedstock, hydrogen production performance of three catalysts was systematically evaluated in a two-stage fixed bed reactor．Results have shown that, compared with catalyst-free control（CK）, all three biochar catalysts effectively promoted tar cracking and increased syngas yield．T₃ catalyst exhibited the best catalytic activity, with tar yield reduced to 239.8 mg/g and gaseous product yield reaching 437.8 mg/g．Gas composition analysis has indicated that H₂ yield and selectivity of T₃ catalyst reached 21.66 mmol/g and 58.23%, respectively, which were higher than those of T₁ catalyst（9.87 mmol/g and 44.97%）and T₂ catalyst（15.35 mmol/g and 51.16%）．Chitin possesses natural nitrogen-containing functional groups and a rich porous structure．After modification with two metals, iron species were successfully loaded and formed slightly agglomerated Fe₂O₃ particles on surface of T₂ catalyst, while a smaller and more uniformly dispersed Fe-Zn composite oxide particles formed on surface of T₃ catalyst．This has indicated that introduction of Zn not only improved single Fe metal dispersibility, but also enhanced biochar catalyst's ability to crack tar through synergistic interaction with Fe, thereby increasing H₂ yield．Fe-Zn bimetallic modified chitin biochar has great application potential in field of biomass catalyzed hydrogen production and offers valuable insights for saving agricultural and forestry resources and promoting high-value utilization of agricultural and forestry wastes．