A theoretical study of thiophenic compounds adsorption on cation-exchanged Y zeolites

► The adsorption desulfurization mechanisms of fuel oils over Cu(I)Y, Ni(II)Y, and Ce(III)Y zeolites have been investigated by a DFT method. ► The η1S and η5 adsorption modes of adsorbate interacted with the cation-exchanged zeolites have been discussed for three different thiophenic compounds. ► The key role of the exchanged metal cations (Cu +, Ni 2+, Ce 3+) on the adsorption behavior was shown. ► The Cu(I)Y zeolite as a sorbent presents the highest adsorption capability compared with the Ni(II)Y and Ce(III)Y zeolites. A density functional theory (DFT) method has been applied to study the adsorption of thiophenic compounds such as thiophene (TP), benzothiophene (BT), dibenzothiophene (DBT) on cation-exchanged Cu(I)Y, Ni(II)Y, Ce(III)Y zeolites. All of calculations were carried out by the generalized gradient approximation (GGA) with the BLYP exchange-correlation functional and DNP basis set. The calculated results indicate that the stable adsorption configuration of TP molecule adsorbed on the Cu(I)Y is the η5 adsorption mode, whereas for BT and DBT, the η1S adsorption mode was found for the both molecules. Only the η1S adsorption mode can be obtained for the three thiophenic compounds adsorbed on the Ni(II)Y. The η5 adsorption mode can be ascribed to the adsorption of thiophene molecules on the Ce(III)Y, but the competition of different adsorption modes could possibly occur during the adsorption process of BT and DBT on the Ce(III)Y. Moreover, the selectivity of TP adsorbed on the adsorbents is in the order of Cu(I)Y > Ce(III)Y > Ni(II)Y, while for BT and DBT, the order is Cu(I)Y > Ni(II)Y > Ce(III)Y.