Desulfurization of Model Diesel Fuel on Activated Carbon Modified with Iron Oxyhydroxide Nanoparticles: Effect of tert-Butylbenzene and Naphthalene Concentrations

Commercially activated carbon Filtrasorb 400 (F400) was modified with iron oxyhydroxide nanoparticles and tested, in a continuous process, as a diesel fuel desulfurization medium. Model diesel fuel (MDF) was prepared as a mixture of decane and hexadecane, with 20 ppm of sulfur from dibenzothiophenes (dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (DMDBT)), and different concentrations of tert -butylbenzene and naphthalene. The calculated selectivities and adsorption capacities for DBT and DMDBT were analyzed at different concentration of aromatics. The results indicate that, while the concentration of naphthalene greatly affects the adsorption capacity of both DBT and DMDBT, the concentration of tert -butylbenzene only affects DMDBT uptake. At low concentration of aromatics, iron-containing carbon performs better than unmodified carbon and further oxidized species were identified on the surface of the iron-modified activated carbon. This indicates that iron is acting as an acidic center, attracting basic DBT and DMDBT, and is acting as an oxidant for the adsorbed species. With an increase in the content of aromatics in MDF, the difference in the desulfurization performance between the studied materials diminishes. After thermal regeneration of the iron-containing sample, 95% of the pore volume is recovered and only a 10% loss in the DBT and DMDBT adsorption capacity is observed.