Desulfurization of liquid fuels by adsorption via π complexation with Cu(I)-Y and Ag-Y zeolites

Fixed-bed adsorption using different,pi-complexation adsorbents for desulfurization of liquid fuels was investigated. Cu(l)-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(l)-Y > Ag-Y > H-Y > Na-Y and Cu(I)-Y > H-Y > Na-Y > Ag-Y, respectively. Cu(l)-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 degreesC, followed by reactivation in helium at 450 degreesC. 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.