Desulfurization of diesel fuel by adsorption via π-complexation using activated carbon and alumina modified with Cu(I) and Ni(II)

Abstract

The adsorptive desulfurization of simulated diesel fuel at DBT concentration of 150 ppm S was studied by using macro and mesoporous alumina (M-Al₂O₃, m-Al₂O₃) and activated carbon (AC) impregnated by Cu(II) and Ni(II), by using the incipient wetness method with an aqueous solution of CuCl₂ and NiCl₂, Cu²⁺ was then reduced to Cu⁺ by H₂. The effect of amount of metal loading was investigated by varying the concentration of metal at 100%, 75% and 50% of the theoretical monolayer surface coverage. The optimum adsorption temperature was found to be 30 ℃ while the optimum flow rate was 0.4 cm³/min. The presence of metal seemed to reduce the breakthrough and adsorption capacity, the lower concentration of metal loading at 50% of the monolayer capacity for both Cu⁺ and Ni²⁺ on alumina showed a higher adsorption capacity than 75% and 100% probably by lowering the accessible porosity in agreement with result from B.E.T. surface area and SEM. Moreover, the smaller size at diameter 300-500 µm which crushed after impregnation of the 100% monolayer of Cu⁺/m-Al₂O₃ showed the higher breakthrough than normal size (extruded length 4 mm) and also higher than the same small size crushed before impregnation. For all among of the adsorbents, the breakthrough capacity decreased in order of 43 wt% of Cu⁺/AC > AC > 100% monolayer of Cu⁺/m-Al₂O₃ (300-500 µm crushed after impregnation) > non-impregnated m-Al₂O₃ > 50% monolayer of Ni²⁺/m-Al₂O₃.