Desulfurization of liquid fuels by adsorption on carbon-based sorbents and ultrasound-assisted sorbent regeneration

Several carbon-based adsorbents, CuCl/AC, PdCl₂/AC, and Pd/AC (where AC denotes activated carbon), were studied for desulfurization of a model jet fuel by selective adsorption of thiophenic molecules. Comparisons with γ-Al₂O₃ support and desulfurization of a commercial jet fuel were also studied. The results showed that the selective sulfur adsorption capacity of PdCl₂ was higher than that of CuCl and Pd ⁰, in agreement with molecular orbital results. It was also found that the activated carbon is the best support for π-complexation sorbents to remove sulfur-containing compounds, i.e., benzothiophene and methylbenzothiophene. Among all the adsorbents studied, PdCl₂/AC had the highest capacity for desulfurization. A significant synergistic effect was observed between the carbon substrate and the supported π-complexation sorbent, and this effect was explained by a geometric effect. The saturated sorbent was regenerated by desorption assisted by ultrasound with a solvent of 30 wt % benzene and 70 wt % n-octane. The results showed that the amount of sulfur desorbed was higher with ultrasound, 65 wt % desorption vs 45 wt % without ultrasound in a static system at 50 °C.