A comparative study on ZIF-8 synthesis in aqueous and methanolic solutions: Effect of temperature and ligand content

ZIF-8, one of the most popular member of zeolitic imidazole frameworks' family is synthesized in aqueous or alcoholic media with different ratios of ligand/metal salt under different temperatures. The impacts of the synthesis parameters were investigated on the phase crystalinity and textural properties of the resultant products. The sodalite phase was detected by XRD analysis and the samples were further analyzed by FESEM, TGA and BET analyses. The results revealed that all parameters e.g. type of solvent, crystallization temperature and ligand content had great impact on the phase purity of the synthesized ZIFs. It was revealed that textural properties and morphology of final products depend mostly on the type of solvent. The dominant morphology of phase pure ZIF-8s obtained in methanolic media was rhombic dodecahedron at 130 °C and ligand/metal ratio of 2, while the synthesis in aqueous medium resulted in a mixture of truncated cubic and rhombic dodecahedron phases at its optimum condition of 25 °C and ligand/metal molar ratio of 4. The highest yield of ZIF-8 was 97% which was obtained from water solution at room temperature.