Insight into the correlation between the effective adsorption sites and adsorption desulfurization performance of CuNaY zeolite

A series of CuNaY zeolites with different Cu loadings were prepared from NaY by liquid-phase ion exchange (LPIE) method. The microstructure and textural properties of CuNaY zeolites were characterized by XRD and N₂ sorption and their adsorption desulfurization performance were evaluated with a model oil containing thiophene by the dynamic adsorption method. Combined with the Py-FTIR and NH₃-TPD methods, the amounts of surface acid sites and effective Cu⁺ species were determined quantitatively and a correlation between the effective adsorption sites and adsorption desulfurization performance of CuNaY zeolite towards thiophene was then established. The results revealed that the surface acidity and the active copper species in Y zeolite can be regulated effectively by controlling the copper loading; an adsorbent provided with abundant effective adsorption sites and excellent adsorption desulfurization performance can be obtained by loading appropriate amount of copper. On the contrary, an excessively high copper loading may promote the formation of polymeric copper species in the cavity of Y zeolite, which leads to a decrease in the number of effective adsorption sites as well as a decrease in the adsorption capacity of CuNaY zeolite towards thiophene.