Abstract:
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 H
2 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 Fe
2O
3 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 H
2 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.