New Sorbents for Desulfurization of Diesel Fuels via π Complexation:  Layered Beds and Regeneration

Desulfurization of a commercial diesel fuel by different layered adsorbents and regeneration of the latter were studied in a fixed-bed unit operated at ambient temperature and pressure. In general, a layered bed consisting of 12 wt % activated carbon, 22 wt % of activated alumina (Selexsorb CDX), followed by Cu(I)−Y, activated carbon/Selexsorb CDX/Cu(I)−Y, is capable of producing 41 cm³ of desulfurized diesel fuel/g of adsorbent. The matrix is capable of processing 27 cm³ of deep-desulfurized diesel with a weighted average content of 76 ppbw S. These low-sulfur fuels are suitable for fuel cell applications. For layered-bed regeneration, it was determined that calcination of the adsorbed sulfur moieties with air at 350 °C followed by autoreduction of the copper species recovered all of the original desulfurization capacity when activated aluminas are used as a guard layer. Solvent elution experiments indicate that carbon tetrachloride and N,N-dimethylformamide are suitable solvents to recover all of the adsorbed organosulfur species.