The economic advantage of membrane-based CO separation technology is more prominent with the development of high-performance membrane materials. The amino-containing fixed carrier membranes with excellent CO separation performance show great potential, especially in post-combustion CO capture. However, the reaction and transport mechanism between CO and amino groups has rarely been systematically investigated due to the limitation of experimental characterization. In this paper, quantum chemistry computations and molecular dynamic simulations are used to analyze the effect of amino density and water in fixed carrier membranes containing primary amino groups. Research result shows that as the spacing between amino groups increases, bicarbonate plays an increasing role in the facilitated transport mechanism due to the gradual increase of reaction energy barrier in carbamate scheme. In the dry PVAm, the reaction energy barrier is 69 % higher than the bicarbonate mechanism and the diffusion coefficient is two orders of magnitude lower than the humid PVAm, which are the reasons for limiting the facilitated transport mechanism and membrane separation performance. Water molecules can provide a polar environment conducive to reactions, directly participate in the reaction process and form highly mobile continuous water clusters for gas high-speed diffusion. Regulating the nitrogen atom spacing of amino group to be less than 3.1 Å and constructing abundant CO transport channels may achieve weakly humidity-dependent facilitated transport membranes.

中文翻译：

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通过计算化学分析氨基密度和水对含氨基固定载体膜的影响

随着高性能膜材料的发展，膜基CO分离技术的经济优势更加凸显。具有优异CO分离性能的含氨基固定载体膜显示出巨大的潜力，特别是在燃烧后CO捕获方面。然而，由于实验表征的限制，CO与氨基之间的反应和传输机制很少被系统地研究。本文利用量子化学计算和分子动力学模拟来分析氨基密度和水对含有伯氨基的固定载体膜的影响。研究结果表明，随着氨基间距的增加，由于氨基甲酸酯方案中反应能垒的逐渐增加，碳酸氢盐在促进传输机制中发挥着越来越大的作用。在干燥的PVAm中，反应能垒比碳酸氢盐机制高69%，扩散系数比潮湿的PVAm低两个数量级，这是限制促进传输机制和膜分离性能的原因。水分子可以提供有利于反应的极性环境，直接参与反应过程并形成高流动性的连续水团簇，供气体高速扩散。调节氨基的氮原子间距小于3.1 Å并构建丰富的CO传输通道可以实现弱湿度依赖性的促进传输膜。