Metal-organic frameworks and their composites for water-alcohol separation applications

The raw product of bio-ethanol is a mixture solution contains both water and alcohol. It needs further purification treatment to separate water and alcohol before it is used as fuel. Metal-organic frameworks (MOFs) form a special class of materials which is highly suitable for molecular separation processes, due to their defined pores can be tailored specifically to enable size and shape selectivity toward guest molecules. In this thesis, there are two systems based on MOFs were developed separately trying to apply in this filed from both chemistry and materials ways.From the chemistry way, two series of alkaline-earth metal based MOFs were synthesized by using two different ligands, 2,5-pyrazinedicarboxylate acid (2,5-H₂pzdc) and tetrakis[4-(carboxyphenyl)-oxamethyl]methane (H₄L). The alkaline-earth metal based MOFs build from 2,5-H₂pzdc displayed three-dimensional (3D) structures with one-dimensional (1D) channels. The coordinated and lattice water molecules in these 1D channels provide them with potential in proton conductivity. Another series of alkaline-earth metal based MOFs constructed by H₄L have capacity in CO₂/N₂ separation which caused by the shrinkage of their flexible frameworks.From the materials way, two composite materials were designed by separately combining the reported MOFs, ZIF-8 and DMOF, together with TiO₂-SiO₂ (TSO) artificial leaf substrate and linear polymer PNIPAM. The ZIF-8@TSO composite displays potential in water-alcohol separation owing to its hierarchical porous structure. The DMOF⊃PNIPAM composite exhibits water-alcohol separation ability due to its designed pore size and affinity.