Desulfurization of Liquid Fuels by Adsorption via π Complexation with Cu(I)−Y and Ag−Y Zeolites

Fixed-bed adsorption using different π-complexation adsorbents for desulfurization of liquid fuels was investigated. Cu(I)−Y (autoreduced Cu(II)−Y), Ag−Y, H−Y, and Na−Y zeolites were used to separate low-concentration thiophene from mixtures including benzene and/or n-octane, all at room temperature and atmospheric pressure. Sulfur-free (i.e., below the detection limit of 4 ppmw sulfur) fuels were obtained with Cu(I)−Y, Ag−Y, and H−Y but not Na−Y. Breakthrough and saturation adsorption capacities obtained for an influent concentration of 760 ppmw sulfur (or 2000 ppmw thiophene) in n-octane follow the order Cu(I)−Y > Ag−Y > H−Y > Na−Y and Cu(I)−Y > H−Y > Na−Y > Ag−Y, respectively. Cu(I)−Y zeolite adsorbed 5.50 and 7.54 wt % sulfur at breakthrough and saturation, respectively, for an influent concentration of 760 ppmw sulfur in n-octane. For the case of 190 ppmw sulfur in mixtures containing both benzene and n-octane, Cu(I)−Y adsorbed 0.70 and 1.40 wt % sulfur at breakthrough and saturation, respectively. Regeneration of the adsorbent was accomplished by using air at 350 °C, followed by reactivation in helium at 450 °C. The observed adsorption behavior, in general, agrees well with previous studies performed for pure-component vapor-phase adsorption of thiophene and benzene with the same adsorbents.