Insight into construction and growth process of core-shell KCHA@ZIF-8 composites

The composites of zeolite@metal organic framework (MOF) have received increasing attention due to their widespread applications. In this study, KCHA@ZIF-8 composites were successfully prepared by using KCHA (zeolite) as the core with coating ZIF-8 (MOF) by a two-step temperature-controlled and surfactant pretreatment method. Various characterizations confirmed the growth of a continuous and well-grown ZIF-8 shell on KCHA surface. Surprisingly, ZIF-8 could grow on KCHA surface in just one minute. Also, the ZIF-8 load thickness could be adjusted by changing the adding amount of KCHA. Interestingly, the resulting composites exhibited excellent hydrophobic properties and maintained the excellent adsorption performance of KCHA core for the separation of CH4/N2. This study would provide a useful reference for the future synthesis of zeolite@MOF composites.