The adsorption configurations of quinoline, acridine, indole and carbazole over Cu(I)Y zeolite were studied by the density functional theory (DFT) method. The eta(2) adsorption mode has been found to be energetically preferred for neutral nitrogen compounds, i.e. indole and carbazole; while for basic ones, quinoline and acridine, the eta N-1 adsorption mode is the most preferential one, implying that in the competitive adsorption aromatics show a strong preference over neutral nitrogen compounds than over basic ones. The adsorption energies of the adsorbate over Cu(I)Y zeolite decrease as follows: basic heterocyclic nitrogen compounds > neutral heterocyclic nitrogen compounds > thiophenic compounds, suggesting that deep denitrogenation and desulfurization could be carried out simultaneously over Cu(I)Y zeolite under ambient temperature, while for Cu(I)Y zeolite the adsorption of nitrogen compounds is preferable to that of sulfur compounds, and good selectivity will be shown for the basic nitrogen compounds during denitrogenation. Meanwhile, when the adsorbent is used for selective deep desulfurization, the presence of nitrogen compounds can greatly retard sulfur removal. (c) 2008 Elsevier B.V. All rights reserved.