Adsorption of thiophene and toluene on NaY zeolites exchanged with Ag(I), Ni(II) and Zn(II)

The present study evaluates the adsorption capacity of thiophene and toluene and their competitive behaviour on zeolite NaY exchanged with transition metals (5 wt% Ni, Zn and Ag). The headspace chromatography technique was used to obtain monocomponent apparent adsorption isotherms of thiophene and toluene with NaY, NiY, ZnY and AgY using isooctane as an inert solvent at 30 and 60 °C. Selectivity between toluene and thiophene at saturation capacities were also measured at 30 °C. The adsorption capacity for thiophene increased for the studied adsorbents as follows: NaY < ZnY < NiY < AgY at 30 °C and NaY < NiY < ZnY < AgY at 60 °C. Toluene is less adsorbed, but within the same order of magnitude as thiophene and following the same sorbent order. All adsorbents were moderately selectivity for toluene. Nevertheless, the sulfur content was successfully reduced in the presence of aromatics and olefins in immersion tests with a model fuel mixture. These results show the importance of inserting transitions metals in the zeolitic structure to enhance the adsorption of both aromatic and sulfur containing compounds in organic liquid mixtures, which shows promise to meet environmental standards in transportation fuels.