Synthesis,characterization, and CO2 adsorption properties of metal organic framework Fe-BDC

The iron-containing Metal–Organic Frameworks (MOFs) have attracted a great deal of attention in the areas of gas separation, catalytic conversion, and drug delivery, due to their high surface area and activity, as well as the non-toxicity of iron. In this study, Fe-based MOFs using BDC ligands, MIL-101(Fe), MIL-53(Fe) and Amino-MIL-101(Fe) are synthesized by a solvothermal method and characterized by conventional methods such as BET, SEM, and TGA. Afterwards, the synthesized MOFs are investigated from the point of view of the adsorbing capability of carbon dioxide at different pressures and temperatures, and also their resistance to water and solvent. The results showed that Amino-MIL-101(Fe) achieved more CO₂ adsorption than MIL-101(Fe) and MIL-53(Fe), equal to 13 mmol g⁻¹ at 4 MP. Although MIL-53(Fe) has the best temperature resistance, around 350 °C, Amino-MIL-101(Fe) is more stable against water and ethanol and its surface area is increased from 670 to 915 m² g⁻¹ after washing with ethanol. The adsorption study reveals that CO₂ is adsorbed not only by a physical adsorption mechanism, but also by chemisorption of acidic carbon dioxide by basic NH₂ agent in the structure of Amino-MIL-101(Fe).

The adsorption isotherm of MIL-101(Fe)-NH₂ was independent of temperature and the heat of adsorption was considered equal to the activation energy of CO₂ chemisorption by NH₂ agent.