Removal of dibenzothiophenes from model diesel fuel on sulfur rich activated carbons

Adsorption of dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (DMDBT) from model diesel fuel with 20 ppmw total concentration of sulfur was investigated on commercial wood based carbon exposed to hydrogen sulfide at 650 °C and 800 °C. The initial and exhausted carbons were characterized using adsorption of nitrogen, thermal analysis, potentiometric titration, FTIR, mass spectroscopy, and elemental analysis. The selectivities for DBT and DMDBT adsorption were calculated with reference to naphthalene. The results showed a marked positive effect of sulfur incorporated to the carbon matrix on the capacity and selectivity for DBT and DMDBT removal from model diesel fuel. This was linked to possible sulfur–sulfur interactions in the whole range of pores. Sulfur in the carbon matrix also contributes to activation of oxygen and oxidation of DBT to sulfoxides and sulfones. Owing to this, not only micropores but also larger pores are active in the selective adsorption.

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► Carbons with incorporated sulfur were used as adsorbents of dibenzothiophenes from model diesel fuel.
► The positive effect of sulfur on the capacity/selectivity of adsorption was found.
► Selectivity was enhanced owing to sulfur–sulfur interactions.
► Sulfur in the carbon matrix contributes to activation of oxygen.
► DBT to sulfoxides and sulfones were found as the products of reactive adsorption.