Hurkmans Jan-Willem, Pelzer Henri M, Burdyny Tom, Peeters Jurriaan, Vermaas David A
Department of Chemical Engineering, Delft University of Technology 2629 HZ Delft The Netherlands
Process & Energy Department, Delft University of Technology 2628 CB Delft The Netherlands.
EES Catal. 2024 Dec 27;3(2):305-317. doi: 10.1039/d4ey00190g. eCollection 2025 Mar 6.
Electrochemical CO reduction offers a promising method of converting renewable electrical energy into valuable hydrocarbon compounds vital to hard-to-abate sectors. Significant progress has been made on the lab scale, but scale-up demonstrations remain limited. Because of the low energy efficiency of CO reduction, we suspect that significant thermal gradients may develop in industrially relevant dimensions. We describe here a model prediction for non-isothermal behavior beyond the typical 1D models to illustrate the severity of heating at larger scales. We develop a 2D model for two membrane electrode assembly (MEA) CO electrolyzers; a liquid anolyte fed MEA (exchange MEA) and a fully gas fed configuration (full MEA). Our results indicate that full MEA configurations exhibit very poor electrochemical performance at moderately larger scales due to non-isothermal effects. Heating results in severe membrane dehydration, which induces large Ohmic losses in the membrane, resulting in a sharp decline in the current density along the flow direction. In contrast, the anolyte employed in the exchange MEA configuration is effective in preventing large thermal gradients. Membrane dehydration is not a problem for the exchange MEA configuration, leading to a nearly constant current density over the entire length of the modeled domain, and indicating that exchange MEA configurations are well suited for scale-up. Our results additionally indicate that a balance between faster kinetics, higher ionic conductivity, smaller pH gradients and lower CO solubility causes an optimum operating temperature between 60 and 70 °C.
电化学一氧化碳还原提供了一种将可再生电能转化为对难以减排的行业至关重要的有价值碳氢化合物的有前景的方法。在实验室规模上已经取得了重大进展，但扩大规模的示范仍然有限。由于一氧化碳还原的能量效率较低，我们怀疑在工业相关尺寸上可能会出现显著的热梯度。我们在此描述一种超越典型一维模型的非等温行为的模型预测，以说明更大规模下加热的严重性。我们为两个膜电极组件（MEA）一氧化碳电解槽开发了一个二维模型；一个液体阳极电解液进料的MEA（交换MEA）和一个全气体进料配置（全MEA）。我们的结果表明，由于非等温效应，全MEA配置在适度更大规模下表现出非常差的电化学性能。加热导致严重的膜脱水，这会在膜中引起大的欧姆损耗，导致电流密度沿流动方向急剧下降。相比之下，交换MEA配置中使用的阳极电解液有效地防止了大的热梯度。膜脱水对于交换MEA配置不是问题，导致在建模域的整个长度上电流密度几乎恒定，这表明交换MEA配置非常适合扩大规模。我们的结果还表明，更快的动力学、更高的离子电导率、更小的pH梯度和更低的一氧化碳溶解度之间的平衡导致最佳操作温度在60至70°C之间。
