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.