As the interest in environmentally-friendly energy processes increases, many studies have been focused on producing hydrogen as an alternative energy carrier via catalytic reaction processes. Sorption enhanced water gas shift (SEWGS) that combines WGS and in situ CO removal is a promising technology for high-purity H production and CO capture. In this study, Fe/Ce-modified CaO-CaAlO bi-functional porous nanotubes were synthesized in one step by template method and applied for H production from SEWGS process. The unique porous nanotube structure fully exposes the catalytic active sites and facilitates the gas-solid transport, resulting in the excellent H production and CO capture performance in SEWGS/regeneration cycles. The introduction of Ce enhances the basicity of the nanotube material, thereby increasing the affinity for CO. The interaction of Fe-Ce improves the redox capability of Fe and Fe, which is beneficial to the conversion of CO. In addition, the formed CaFeO and CaCeO both increase the concentration of oxygen vacancies, further enhancing the SEWGS reactivity of the material. The optimal molar ratio of Fe/Ce/Al/Ca is 10/3/10/100, and the CO conversion, H concentration, CO capture capacity of the Fe/Ce-modified bi-functional material were 76.9 %, 70.1 % and 83.2 % after 20 cycles. The effect of Fe/Ce doping on CaO-based materials was investigated at the molecular level using density functional theory (DFT). The results demonstrate that the addition of Ce can effectively maintain the stable structure of Fe-CaO-based materials. The modification of Fe/Ce is expected to promote efficient H generation from CaO-based materials through the SEWGS process.

中文翻译：

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钙循环过程中掺杂铁和铈的钙基吸附剂的 CO2 捕集和产氢性能


随着人们对环保能源过程的兴趣不断增加，许多研究都集中在通过催化反应过程生产氢气作为替代能源载体。吸附增强水煤气变换 (SEWGS) 将 WGS 和原位 CO 去除相结合，是一种很有前景的高纯 H 生产和 CO 捕集技术。本研究采用模板法一步合成了Fe/Ce修饰的CaO-CaAlO双功能多孔纳米管，并应用于SEWGS工艺制氢。独特的多孔纳米管结构充分暴露催化活性位点并促进气固传输，从而在SEWGS/再生循环中产生优异的H产生和CO捕获性能。 Ce的引入增强了纳米管材料的碱性，从而增加了对CO的亲和力。Fe-Ce的相互作用提高了Fe和Fe的氧化还原能力，有利于CO的转化。此外，形成的CaFeO和CaCeO均增加了氧空位的浓度，进一步增强了材料的SEWGS反应活性。 Fe/Ce/Al/Ca的最佳摩尔比为10/3/10/100，Fe/Ce修饰双功能材料的CO转化率、H浓度、CO捕获能力分别为76.9%、70.1%和20 个循环后为 83.2%。使用密度泛函理论 (DFT) 在分子水平上研究了 Fe/Ce 掺杂对 CaO 基材料的影响。结果表明，Ce的添加可以有效保持Fe-CaO基材料的稳定结构。 Fe/Ce 的改性有望通过 SEWGS 工艺促进 CaO 基材料的高效产氢。