The exploration of NiO/Ca2Fe2O5/CaO in chemical looping methane conversion for syngas and H2 production
The exploration of NiO/Ca2Fe2O5/CaO in chemical looping methane conversion for syngas and H2 production
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DOI：
10.1016/j.cej.2023.142779
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发表时间：
2023-04
影响因子：
15.1
通讯作者：
Yaoyao Zheng;Made Santihayu Sukma;S. Scott
中科院分区：
文献类型：
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作者：
Yaoyao Zheng;Made Santihayu Sukma;S. Scott
用于化学循环的材料可用于以多种方式处理甲烷。在固体材料上使用氧气会导致部分或全部氧化，而甲烷在耗尽的固体上裂解成碳会产生氢气。如果使用 CO2 或 H2O 作为氧化剂，则固体再生以除去裂化的碳或恢复氧气可以产生 CO、H2 或组合。化学循环材料将甲烷的转化与氧气的添加分开。含有 CaO 等吸附剂的材料可以与产生的 CO2 相互作用，以所需的方式改变平衡。这些材料可用于配置循环过程，该过程是 DRM、SMR 和裂化与固体燃烧再生的线性组合。在此，研究了一种结合催化剂（即 Ni）、氧载体（即 Ca2Fe2O5）和 CaO 的材料，用于在循环 DRM 过程中将甲烷转化为合成气或富氢气体。在第一阶段，甲烷在 NiO/Ca2Fe2O5/CaO 流化床中转化为合成气或 H2，固体在例如 700 °C 的温度下被还原/碳酸化；在第 2 阶段，还原/碳酸化材料在 900 °C 下再生。 Ni-Ca-Fe-O 系统的热力学允许 Ni 与 Ca2Fe2O5 保持分离，这意味着 CaO 抑制 Ni 和 Fe 的任何混合氧化物相的形成。 NiO/Ca2Fe2O5/CaO 被激活后，发现合成气或 H2 的高产率（取决于第一阶段的不同阶段）。活化的 NiO/Ca2Fe2O5/CaO 在 30 多个循环中产生大量合成气或 H2，而没有材料失活。 CH4 处理过程中形成碳晶须，但不会导致失活。
Materials used for chemical looping can be exploited to process methane in a number of ways. Using the oxygen on the solid material leads to partial or total oxidation, whilst methane cracking to carbon on the depleted solid can produce hydrogen. Regeneration of the solid to remove the cracked carbon or restore the oxygen can produce CO, H2or a combination if CO2or H2O is used as the oxidant. The chemical looping material separates the conversion of methane from the addition of oxygen. Materials containing sorbents like CaO can interact with the CO2produced to shift the equilibrium in desirable ways. These materials could be utilised to configure a cyclic process that is a linear combination of DRM, SMR, and cracking with combustive regeneration of the solid. Here, a material combining a catalyst (i.e.Ni), an oxygen carrier (i.e.Ca2Fe2O5) and CaO was investigated for converting methane to syngas or hydrogen-rich gas in a cyclic DRM process. In Stage 1, methane is converted to syngas or H2in a fluidised bed of NiO/Ca2Fe2O5/CaO, where the solid is reduced/carbonated at,e.g., 700 °C; in Stage 2, the reduced/carbonated material is regenerated at 900 °C. The thermodynamics of the Ni-Ca-Fe-O system allows Ni to stay separate from Ca2Fe2O5, meaning that CaO inhibits the formation of any mixed oxide phase of Ni and Fe. A high rate of production of syngas or H2(depending on different phases of Stage I) was found after the NiO/Ca2Fe2O5/CaO became activated. The activated NiO/Ca2Fe2O5/CaO gave high production of syngas or H2for over 30 cycles without material deactivation. Carbon whiskers formed during CH4processing, and did not cause deactivation.