Combination of amino functionalized metal organic framework with nitrogenous compounds in model fuel

The metal-organic frameworks, MIL-53 (Al)-NH₂ and MIL-53 (Al), were synthesized and used as the adsorbents for the removal of nitrogen-containing compounds (quinoline and pyrrole) from model fuel. The adsorbents were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), FT-IR spectroscopy, and thermogravimetric analysis. Compared with the adsorption capacity of MIL-53 (Al), MIL-53(Al)-NH₂ possesses a higher adsorption capacity for quinoline and pyrrole in the model fuel due to the hydrogen bonding interaction between MIL-53(Al)-NH₂ and the nitrogen-containing compounds. The factors affecting the adsorption capacity are the adsorptive time and temperature. Furthermore, the pseudo-first-order and pseudo-second-order adsorption kinetics models were tested. It is found that the pseudo-second-order kinetics model is preferable to characterize the adsorption process. The adsorption isotherms and adsorption thermodynamics of quinoline and pyrrole on the MIL-53(Al)-NH₂ were also evaluated. The calculation of separation factor R_L and thermodynamic parameters (ΔG⁰, ΔH⁰和ΔS⁰) show that the adsorption of quinoline/pyrrole on the MIL-53(Al)-NH₂ is a spontaneous and exothermic process. The used MIL-53 (Al)-NH₂ could be regenerated by simple solvent washing with ethanol and reused in the adsorption process.