Effect of Water Adsorption on Retention of Structure and Surface Area of Metal-Organic Frameworks

This work presents an experimental investigation of water adsorption in metal organic frameworks (MOFs) at room temperature and up to 90% relative humidity. Structural degradation of the materials after regeneration is analyzed via powder X-ray diffraction (PXRD) and nitrogen adsorption measurements. MOFs with open metal sites are quite hydrophilic but appear to maintain their structure according to PXRD. However, significant surface area loss indicates that decomposition is occurring and is likely an attribute of oxygen presence during the regeneration procedure. Materials with copper paddle-wheel (HKUST-1), 5-coordinated magnesium (Mg MOF-74), and 7-coordinated zirconium (UiO-66(-NH2)) maintain good structural stability, while Zn-COOH containing MOFs (DMOF-1; DMOF-1-NH2; UMCM-1) undergo complete loss of crystallinity.