Effect of desilication of NaY zeolite on sulfur content reduction of gasoline model in presence of toluene and cyclohexene

Abstract

The presence of sulfur compounds in transportation fuels have always been one of the most important issues discussed in scientific and industrial associations. In recent years, due to the adoption of global policies to address environmental problems, the study of efficient systems for desulfurization of fuels has attracted much attention. In this study, the effects of alkaline treatment with NaOH and NaOH/TPAOH mixtures with different concentrations on adsorption desulfurization of NaY adsorbent were investigated. The adsorbents were characterized by XRD, FE-SEM, BET, EDX, ICP-OES and FT-IR techniques. It was found that alkaline treatment in the NaOH/TPAOH solution with TPAOH/(TPAOH + NaOH) = 0.5 had the highest total surface area followed by the highest adsorption capacity among the desilicated adsorbents. In order to increase the adsorption capacity, copper and cerium metals were impregnated individually and in pairs on this adsorbent at 80 °C. The results showed that impregnating of metal ions increases the adsorption capacity of adsorbents so that CuCe-0.5R adsorbent with values of 21.02 and 24 mg/g had the highest adsorption capacity of thiophene and dibenzothiophene sulfur compounds, respectively. In this regard, the competitive adsorption of toluene and cyclohexene was also investigated in different model fuels containing isooctane as a solvent. The adsorption capacity reduction of sulfur compounds for different adsorbents was in order of Cu-0.5R > CuCe-0.5R > Ce-0.5R, respectively, in the presence of toluene and cyclohexene. Thermodynamics studies showed that the adsorption process is endothermic. The kinetic models in adsorbing the sulfur compounds followed the pseudo-second-order equation.