We report on an electrochemically driven CO₂ separation process employing commercial anion exchange membranes to directly remove CO₂ from a dilute gas mixture and transport it across a cell. This methodology exploits the carbonation behavior of alkaline membrane systems to react CO₂ with hydroxide ions generated through the hydrogen evolution reaction and form (bi)carbonate ions. Electrochemically pumped (bi)carbonate then evolves as CO₂ on the anode side through the hydrogen oxidation reaction with H₂. The resulting mixture of CO₂ and residual H₂ could be utilized for downstream valorization processes. Cell polarizations with 0.1–100% CO₂ in N₂ as the feed gas were performed with current densities of up to 50 mA·cm^–2, and CO₂ concentrations were monitored using online gas analysis. Further experiments examining the effect of pumping against pressure and concentration gradients were performed, along with Pd wire reference electrode experiments to discern cathode and anode overpotentials. Additional fundamental techno-economic considerations are presented to explore the cost dynamics of the system and the relevant targets for cell operation. The results show the complex interactions between cell input and performance parameters, as well as some of the critical limitations that must be overcome to allow for process scale-up to become viable.

中文翻译：

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使用膜电化学池从稀薄气流中分离CO ₂

我们报告了一种电化学驱动的CO ₂分离工艺，该工艺采用了工业上的阴离子交换膜直接从稀释的气体混合物中去除CO ₂并将其运输通过整个电池。该方法利用了碱性膜系统的碳酸化行为，使CO ₂与通过氢释放反应产生的氢氧根离子发生反应，并形成碳酸氢根离子。然后，电化学泵送的碳酸氢根盐通过与H ₂的氢氧化反应在阳极侧以CO ₂的形式析出。所得的CO ₂和残留的H _2的混合物可用于下游的增值过程。0.1至100％CO _2的细胞极化在N _2中作为进料气以最高50 mA·cm ^–2的电流密度进行操作，并使用在线气体分析监测CO ₂浓度。进行了进一步的实验，研究了泵对压力和浓度梯度的影响，以及钯线参比电极实验，以辨别阴极和阳极的超电势。提出了其他基本的技术经济考虑因素，以探索系统的成本动态以及电池操作的相关目标。结果表明，单元输入和性能参数之间的复杂相互作用，以及必须克服的一些关键限制才能使工艺放大成为可行。