Adsorptive removal of aromatic organosulfur compounds over the modified Na-Y zeolites

The adsorptive removal of organosulfur compounds including dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT) on the various ion-exchanged Na-Y zeolites (with single Cu2+, Zn2+, Ag+ and the combined Cu2+–Zn2+, Zn2+–Nd3+, Ni2+–Nd3+) in the model systems (the n-octane solutions of sulfur compounds and in some cases with small fraction of benzene/toluene) has been systematically compared. The pre-oxidation of the sulfur compounds together with adsorption procedure over Ag-Y and CuZn-Y adsorbents and the solo-oxidation of the sulfur compounds without adsorption were also performed for comparison. It was observed that the desulfurization efficiency follows the order of direct adsorption > oxidation-adsorption > direct-oxidation. The CuZu-Y was found to be a promising competitor to Ag-Y in terms of the desulfurization performance, and the former is more stable than the latter. The influence of various parameters on desulfurization of Ag-Y and CuZn-Y was investigated. The characterization results of the fresh and used samples provide insights into the characteristics of various adsorbents and the sort of interactions between the adsorbed sulfur compounds and the exchanged metal ions. A full regeneration of used Ag-Y can be achieved by air-calcination at 450 °C.