New hybrid approach for desulfurization of diesel fuel using an efficient heterogeneous polyoxometalate nanocatalyst

Abstract

In this manuscript, the catalytic oxidative desulfurization (CODS) process was proposed to reduce the remove the thiophene (T) and benzothiophene (BT) in diesel fuel. An organic-inorganic hybrid nanocatalyst has been synthesized using 1-Methylimidazolium (MZ) as a transfer agent, CuO nanoparticles as a support, and the highly active mono copper-substituted polyoxotungstate ([PW11CuO39], abbreviated as PW11Cu). Catalytic oxidative desulfurization involves the simultaneous use of extraction technique by an ionic liquid ([BMIM][PF6]) and catalytic oxidation by a suitable heterogeneous catalyst. The experimental condition was optimized by response surface methodology. The removal efficiency in the compounds was as follows: T < BT. In addition, the kinetic behavior of the removal of all sulfur compounds was according to a quasi-first-order model. The nanocomposite was prepared via sol-gel method and finally calcined at 400 °C for 4 h. The materials characterized by means of FT-IR, UV–vis, XRD, and SEM techniques. The response optimization for extractive-catalytic oxidative desulfurization was performed for the removal efficiency of T and BT. The optimum condition was determined as 14.43 min, 40.52 °C for reactor temperature, 86.27 mg for nanocatalyst dosage and 23.99% for oxidant concentration. According to the obtained results, the removal efficiency of thiophene and benzothiophene of diesel fuel could reach 98% and 99%, respectively. The synthesized heterogeneous nanocatalyst could be separated and recycled successfully after 5 times. This system is suggested as an effective strategy with a great potential in the preparation of clean gasoline fuel.