Andirova Dinara, Lei Yu, Zhao Xiaodan, Choi Sunho
Department of Chemical Engineering, Northeastern University, 313 Snell Engineering Center, 360 Huntington Avenue, Boston, MA, 02115-5000, USA.
ChemSusChem. 2015 Oct 26;8(20):3405-9. doi: 10.1002/cssc.201500580. Epub 2015 Sep 14.
Metal-organic frameworks (MOFs) have been highlighted recently as promising materials for CO2 capture. However, in practical CO2 capture processes, such as capture from flue gas or ambient air, the adsorption properties of MOFs tend to be harmed by the presence of moisture possibly because of the hydrophilic nature of the coordinatively unsaturated sites (CUSs) within their framework. In this work, the CUSs of the MOF framework are functionalized with amine-containing molecules to prevent structural degradation in a humid environment. Specifically, the framework of the magnesium dioxybenzenedicarboxylate (Mg/DOBDC) MOF was functionalized with ethylenediamine (ED) molecules to make the overall structure less hydrophilic. Structural analysis after exposure to high-temperature steam showed that the ED-functionalized Mg/DOBDC (ED-Mg/DOBDC) is more stable under humid conditions, than Mg/DOBDC, which underwent drastic structural changes. ED-Mg/DOBDC recovered its CO2 adsorption capacity and initial adsorption rate quite well as opposed to the original Mg/DOBDC, which revealed a significant reduction in its capture capacity and kinetics. These results suggest that the amine-functionalization of the CUSs is an effective way to enhance the structural stability of MOFs as well as their capture of humid CO2 .
金属有机框架材料（MOFs）最近已成为二氧化碳捕获的有前景的材料。然而，在实际的二氧化碳捕获过程中，例如从烟道气或环境空气中捕获，MOFs的吸附性能往往会因水分的存在而受到损害，这可能是由于其框架内配位不饱和位点（CUSs）的亲水性所致。在这项工作中，MOF框架的CUSs用含胺分子进行功能化，以防止在潮湿环境中结构降解。具体而言，用乙二胺（ED）分子对二氧苯二甲酸镁（Mg/DOBDC）MOF的框架进行功能化，以使整体结构的亲水性降低。高温蒸汽暴露后的结构分析表明，与经历了剧烈结构变化的Mg/DOBDC相比，ED功能化的Mg/DOBDC（ED-Mg/DOBDC）在潮湿条件下更稳定。与原始的Mg/DOBDC相比，ED-Mg/DOBDC很好地恢复了其二氧化碳吸附容量和初始吸附速率，而原始的Mg/DOBDC的捕获容量和动力学则显著降低。这些结果表明，CUSs的胺功能化是提高MOFs结构稳定性及其对潮湿二氧化碳捕获能力的有效方法。
