Synthesis And Characterization Of Zeolitic Imidazolate Frameworks

Zeolitic imidazolate frameworks (ZIFs) are imidazole-containing coordination polymers which belong to a kind of metal-organic framework (MOFs) materials. These materials ZIFs have important scientific research and industrial applications because of the diversity of composition, higher thermal and chemical stability and excellent selectivity for capturing carbon dioxide. This thesis aims at synthesis and characterization of the new materials, and their adsorption/desorption, thermal and chemical stability are also performed. The study are as below:1. Solvothermally, ZIF-4 was synthesized as crystals by copolymerization of Zn(II) with imidazolate links. The effects of interior wall of contains, the order of mixed reaction chemicals and synthetic pressure on the morphology development were experimentally examined. The products were systematically characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermogravimetry (TGA). Thermal stability and chemical stability in methanol of ZIF-4 were employed.2. Solvothermally, different synthetic parameters of ZIF-8 have been employed, such as materials of interior wall of contains, synthetic scales, the order of mixed reaction chemicals. The structure and physical characterization of ZIF-8 were studied by SEM, XRD and low temperature N2 adsorption and desorption methods. Hydrothermal stability of ZIF-8 in high temperature water vapor and chemical stability of ZIF-8 in ethanol were carried out, in comparison with typical H-SZM-5.3. Synthesizing new ZIFs by changing the metal ion or imidazole ligand was explored. 4-methylimidazole as an organic ligand coordinated with Zn(â…¡) was investigated with different crystallization time and different ratio of the case. Coordination polymerization condition of Co(â…¡) with imidazole or 2-methylimidazole has been investigated respectively.4. Nanocrystals of ZIF-8 was synthesized. We also explored the synthesis of zeolitic imidazolate framework membrane on the suface of mesoporous MCM-41, microporous AlPO4-5 or porous Al2O3 with ZIF-8.