Adsorption of dibenzothiophenes on activated carbons with copper and iron deposited on their surfaces

Three polymer-derived carbons with iron and different amounts of copper on the surface were investigated as adsorbents of dibenzothiophene (DBT) and 4, 6-dimethyldibenzothiophene (DMDBT) from simulated diesel fuel. To characterize the initial and exhausted carbons nitrogen adsorption, elemental analysis, X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermal analysis (TA) were applied. The selectivities for DBT and DMDBT were calculated with reference to naphthalene. In spite of the enhancement in selectivity for DBT and DMDBT removal caused by iron and copper species, the results indicate that the volume of micropores is the main factor governing the amount adsorbed. Oxidation of benzothiophenes is likely promoted by iron oxide and copper/copper oxide highly dispersed on the surface. The oxidation products are then selectively adsorbed on the surface of carbon in larger pores where metal species and heteroatoms are the active centers for adsorption of polar species.