Synthesis of Mixed-Ligand Zeolitic Imidazolate Framework (ZIF-8-90) for CO₂ Adsorption

Microporous metal–organic frameworks (MOFs) exhibit advantages on gas adsorption and catalysis of small molecules owing to high surface area and suitable pore size. One of the members in MOF, zeolitic imidazolate framework (ZIF), has attracted much attention in recent days, and different kinds of ZIFs had been synthesized with single organic linker. However, only few reports discussed the effect of mixed linkers. In this research, we synthesized mixed linker ZIF structure, ZIF-8-90. Different mole percentage of 2-methylimidazole and 2-imidazolecarboxaldehyde were mixed together to form ZIF-8-90 X %. We found that DMF had good effect on controlling the particle size but reducing the productivity ratio. The ZIF-8-90 X % NPs had different physical properties, such as surface area, pore size distribution and gas adsorption. The results showed that ZIF-8-90 30 and 50 % were the better adsorbents for CO₂ adsorption (2.37 and 2.82 mol/g, respectively) at room temperature, as compared with other microporous framework, MIL-series, HKUST-1, ZIF-100.