Preparation of a Composite Material AC/Cu-BTC with Improved Water Stability and n-Hexane Vapor Adsorption

The Cu-BTC, a widely studied metal-organic framework (MOF), has been applied in various fields such as gas adsorption, separation, storage, and catalysis. However, the Cu-BTC collapses due to the replacement of the organic linker by water molecules under humid conditions, which limits its practical application in industries. In consideration of the undesirable water effect on the framework stability of Cu-BTC, a stable activated carbon (AC) was incorporated into it by the in situ method to yield a composite material AC/Cu-BTC with high water stability. XRD and SEM patterns proved that the AC_7%/Cu-BTC successfully retains its crystal structure after being exposed to water molecules. The adsorption amount of n-hexane vapor of the AC_7%/Cu-BTC after water vapor adsorption-thermal desorption is 307% of that of the Cu-BTC. The addition of the AC changes the adsorption active sites and reduces the strong affinity of the Cu-BTC to water molecules, resulting in the AC_7%/Cu-BTC having a much lower adsorption rate for water vapor than the Cu-BTC. Therefore, the AC_7%/Cu-BTC can be protected from a large amount of water molecules and avoid structural collapse caused by the disconnection between the copper center and the organic linker. The composite displays a potential value for stable applications of MOF-based materials under ambient conditions.