The sorption-enhanced steam methane reforming (SE-SMR) process is promising for in situ CO₂ capture and high-purity hydrogen production with a low CO concentration. SE-SMR using a CaO-based sorbent was operated at a temperature of 600–750 °C. High-purity H₂ production (defined as the H₂ molar fraction at outlet ≥90%) by SE-SMR using a CaO sorbent is generally not achievable at a temperature of 550 °C with a commonly used steam/methane molar ratio (S/C) of 3. CO₂ is the main greenhouse gas. The utilization of CO₂ to improve high-purity H₂ production through SE-SMR by adding CO₂ at the inlet in a fixed-bed reactor at 550 °C and S/C = 3 is numerically studied. The results show that high-purity H₂ production is achieved when the extra CO₂ addition at the inlet is at least 12% of the original mass flow rate (denoted as ≥12% CO_2,in), based on the parameters in this work. The remarkably higher reaction rate of the strongly exothermic CO₂ sorption reaction is obtained for CO_2,in ≥ 12% in the inlet region of the catalyst/sorbent bed for the earlier time stage. Consequently, the temperature and the rate of steam methane reforming are significantly enhanced by the CO₂ sorption reaction. CH₄ conversion, the rates of H₂ production and CaO conversion, and total H₂ production (based on per unit mass of supplied CH₄) are enhanced by an increase in the level of CO_2,in.

中文翻译：

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在低于 600 °C 的温度下通过添加 CO2 进行吸附强化蒸汽甲烷重整生产高纯度氢气

吸附强化蒸汽甲烷重整(SE-SMR)工艺有望用于原位CO ₂捕获和低CO浓度的高纯度氢气生产。使用 CaO 基吸附剂的 SE-SMR 在 600–750 °C 的温度下运行。使用CaO吸附剂通过SE-SMR生产高纯度H ₂（定义为出口处的H ₂摩尔分数≥90%）通常在550℃的温度下以常用的蒸汽/甲烷摩尔比（S /C) of 3. CO ₂是主要温室气体。对在550℃、S/C=3的固定床反应器入口处添加CO ₂，​​通过SE-SMR利用CO ₂提高高纯H ₂产量进行了数值研究。结果表明，根据本文中的参数，当入口处额外添加的 CO _{2至少为原始质量流量的 12%（表示为 ≥12% CO 2,in ）时，即可实现高纯度 H 2}生产。工作。对于早期阶段的催化剂/吸附剂床的入口区域中的CO _2,获得了明显更高的强放热CO ₂吸附反应的反应速率，≥12%。因此，CO ₂吸附反应显着提高了蒸汽甲烷重整的温度和速率。 CH _{4转化率、H 2}产量和CaO转化率以及总H ₂产量（基于每单位质量的供应CH _{4 ）通过CO 2,in}水平的增加而增强。