Effect of Loading on the Water Stability of the Metal–Organic Framework DMOF-1 [Zn(bdc)(dabco)_0.5]

Abstract

In this work, the degradation of the metal–organic framework (MOF) DMOF-1 as a function of water adsorption was investigated. As the quantity of water vapor adsorbed by DMOF-1 increases, degradation of the MOF from hydrolysis accelerates. Degradation was attributed to clustering of water molecules in the void space of DMOF-1, as seen in NVT Monte Carlo simulations. Our molecular simulations strongly suggest that degradation of DMOF-1 by water is driven by water adsorption at defect sites in the MOF. Interestingly, it was observed that DMOF-1 can remain stable if it adsorbs less water than the 1 mmol/g necessary to initiate degradation within the framework. Even though the rate of hydrolysis increases at higher temperatures, the degradation threshold for DMOF-1 remains 1 mmol/g regardless of temperature. This suggests that at sufficiently elevated temperatures (above ∼50 °C) DMOF-1 is stable toward water vapor at all relative humidities.

Adsorptive Separation of CO2 by a Hydrophobic Carborane-Based Metal–Organic Framework under Humid Conditions

“…Although these MOFs do not contain free coordination sites for water to readily interact with, they are not stable under >60% relative humidity at RT. Degradation seems to be related to water adsorption at defect sites in the MOFs . Considering water one of the most common contaminants, the possibility of performance in its presence is a relevant parameter for implementation in the current separation industry.…”

“…Degradation seems to be related to water adsorption at defect sites in the MOFs. 64 Considering water one of the most common contaminants, the possibility of performance in its presence is a relevant parameter for implementation in the current separation industry.…”

Adsorption and Removal of Industrial Dyes by Water-Stabilized Aluminum-Based Metal–Organic Frameworks

“…21 DMOF-1 is of interest because of its unique structure, but it starts to degrade when it comes into contact with water vapor, so it cannot be used in an aqueous phase environment. 22 Second, most MOF materials are made of heavy metal salts, which are expensive and unfavorable for application. For example, the cost of raw materials required for the preparation of zirconium-based MOFs, which are well known for their excellent water stability, is too high, which is the main obstacle to their practical application.…”

“…For example, although MOF-5 can adsorb pollutants in water, it does not exist stably in water, leading to its poor reusability . DMOF-1 is of interest because of its unique structure, but it starts to degrade when it comes into contact with water vapor, so it cannot be used in an aqueous phase environment . Second, most MOF materials are made of heavy metal salts, which are expensive and unfavorable for application.…”

Efficient Generation of Large Collections of Metal–Organic Framework Structures Containing Well-Defined Point Defects

“…Hossain et al studied the impact of defects on CO 2 and water adsorption in UiO-66 and found that defect sites have a greater influence on low-pressure CO 2 adsorption in MOFs than the coadsorption of water, thus altering the selectivity of the MOF . In a study of water adsorption of DMOF-1 by Chen et al, the presence of defects explained the water intrusion phenomenon observed experimentally . Cai and Sholl showed that point defects in Zn­(tbip) are responsible for the unexpected molecular diffusion behavior in this MOF’s 1D channels and that missing water defects play a pivotal role in the interesting separation phenomena that are possible with the MOF UTSA-280 …”