۱- Introduction

۲- Materials and methods

۳- Results and discussions

۴- Conclusions

References

Abstract

In the present study, dual-functional CuO–Fe3O4 magnetic nanocomposites (MNCs) have been prepared through a simple impregnation method and used as catalyst for photocatalytic oxidative desulfurization of model-fuel (dibenzothiophene, DBT in n-hexane) and real naphtha at moderate conditions. The CuO–Fe3O4 MNCs were characterized by X-ray diffraction, BET surface area and pore volume using nitrogen adsorption–desorption and VSM methods The effects of different reaction parameters such as initial DBT concentration in model-fuel, CuO–Fe3O4 MNCs dose, reaction time, H2O2/DBT molar ratio and CuO:Fe3O4 weight ratio of the MNCs were studied in detail. Results for model-fuel treatment showed that the prepared nanocomposite can eliminate 95.2% of DBT after 120 min under the following conditions: CuO:Fe3O4 weight ratio of 1:1, catalyst dose of 10 g/l, H2O2/DBT mole ratio of 7.5:1 and initial DBT concentration of 250 mg/l. Furthermore, 93% of sulfur conversion was obtained for naphtha fuel (initial sulfur concentration of 533 mg/l) after 240 min reaction time. The synthesized CuO–Fe3O4 magnetic nanocomposites combines the photocatalytic activity of CuO and the adsorption capacity of both Fe3O4 and CuO species, which make it have important applications in the deep desulfurization of liquid fuels.

Introduction

Existence of sulfur in liquid petroleum fuels may cause several significant problems such as catalyst poisoning in many oil refining processes. Furthermore, it’s a main cause of corrosion in pumping, pipeline and burners. During combustion, liquid fuels, which contain high levels of sulfur, will generate SOx emissions which are the main source of environment pollution and acid rains [1-3]. Consequently, removing of sulfur compounds (such as thiols, sulfides, and thiophenic compounds) from liquid fuels is highly significant in the petroleum refining industry. Conventionally, hydrodesulfurization (HDS) process have been proposed for removing of sulfur from liquid fractions using catalyst under high temperature and pressure in the presence of hydrogen gas. HDS process is highly effective for the reduction of thiols, sulfides and disulfide, but aromatic sulfur compounds such as thiophene and its derivatives are recalcitrant and less reactive in HDS process [4, 5]. So as to meet the ultra-low sulfur level rules, the refractory thiophenic compounds should also be removed. HDS is very expensive and it is carried out under high conditions of temperature and pressure to be able to desulfurize these refractory sulfur compounds [6]. Numerous improving techniques such as reactive adsorption, extraction, biodesulfurization, and oxidative desulphurization are recommended to complement the conventional HDS process for clean fuels production [7]. Due to the availability of the required materials with no expensive operating conditions as in HDS, Oxidative desulfurization (ODS) is considered to be one of the favorable techniques for deep desulfurization of liquid petroleum fuels [8-12]. The photocatalytic oxidative desulfurization is attracting particular interest, due to its low operating cost and moderate conditions [13].