The introduction of nitrogen-containing heterocyclic compounds (NHC) and Cu2+ in Co-MOF further improves the removal of dibenzothiophene from model fuels

Abstract

NHC/Co-MOF-Cu2+ composite adsorbent materials were prepared through the in-situ synthesis of nitrogenous heterocyclic compounds (NHC) on Co-containing metal–organic framework (Co-MOF) using terephthalaldehyde (C8H6O2) and p-Phenylenediamine (C6H8N2) at room temperature. Subsequently, further modification with Cu2+ was carried out. These materials were then utilized for the removal of dibenzothiophene (DBT) from simulated gasoline. The samples were analyzed using scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR) and other methods. The results indicated the uniform attachment of NHC and Cu2+ metal particles onto Co-MOF, confirming the successful synthesis of NHC/Co-MOF-Cu2+ adsorption materials. The introduction of Cu2+ enhanced the π-complexation between NHC/Co-MOF-Cu2+ and DBT. The introduction of NHC brought heteroatoms and ring structures to the composite, increasing the electron cloud density of the NHC/Co-MOF-Cu2+ composite and thereby amplifying the π-complexation with DBT. The adsorption capacity of NHC/Co-MOF-Cu2+ for DBT (150.4 mg/g) is significantly larger than that of Co-MOF (102.5 mg/g). The adsorption process of NHC/Co-MOF-Cu2+ for DBT followed the pseudo-second-order kinetic model and Langmuir model. Additionally, the adsorption process was found to be spontaneous and exothermic. Over five consecutive adsorption–desorption cycles, the efficiency of NHC/Co-MOF-Cu2+ decreased by only 10 %, indicating its excellent regeneration performance.