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铁锌改性甲壳素生物炭催化重整制氢研究

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

  • 摘要: 为探究制备高效热解制氢生物炭催化剂,以天然富氮原料甲壳素为前驱体,铁、锌为金属负载源,通过一步浸渍−炭化法制备甲壳素生物炭(T1催化剂)、硝酸铁负载炭(T2催化剂)和铁锌负载炭(T3催化剂)3组生物炭催化剂。以稻壳为原料,在两段式固定床反应器中,系统评价3组催化剂的制氢性能。试验表明,与无催化剂(CK)相比,3组催化剂均能有效促进焦油裂解,提高合成气产率。T3催化剂表现出最佳催化活性,焦油产量降低至239.8 mg/g,气相产物产量达到437.8 mg/g。通过气体组分分析,T3催化剂的H2产率和选择性分别达到21.66 mmol/g和58.23%,高于T1催化剂的9.87 mmol/g和44.97%、T2催化剂的15.35 mmol/g和51.16%。甲壳素具有天然的含氮官能团和丰富的孔隙结构,通过两种金属分组改性后,铁物种成功负载并在T2催化剂表面形成略微团聚的Fe2O3颗粒,T3催化剂表面则形成粒更小分散更均匀的铁锌复合物颗粒,表明锌的引入不仅改善了单一金属铁的分散性,通过与铁的协同作用,增强了生物炭催化剂对焦油裂解的能力,提升了H2产率。铁锌双金属改性甲壳素生物炭在生物质催化制氢领域具有较大应用潜力,对节约农林资源,推动实现农林废弃物高值化利用具有借鉴意义。

     

    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 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.

     

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