مهيار منصوري

In the present study, the removal of refractory sulfur compounds from real diesel fuel was investigated through an oxidative–extractive desulfurization process using phosphomolybdic acid (PMA)-modified HZSM-5 as a heterogeneous catalyst. ZSM-5 zeolite was successfully synthesized from kaolin as an inexpensive mineral precursor an‎d subsequently converted into an active heterogeneous catalyst via PMA loading. Structural an‎d physicochemical characterization by XRD, FTIR, SEM-EDX, BET, TGA, an‎d XRF confirmed that the crystalline framework of the zeolite was preserved an‎d that molybdenum species were well dispersed over the support. The catalytic results demonstrated that the presence of HZSM-5-PMA significantly enhanced sulfur removal efficiency compared with the homogeneous hydrogen peroxide/formic acid system, which was attributed to more effective oxidant activation. Experiments conducted on real diesel with an initial sulfur content of 329 ppm showed that the combined oxidation an‎d extraction using dimethylformamide enabled efficient removal of refractory aromatic sulfur compounds. Optimization via response surface methodology (Box–Behnken design) revealed the significant effects of the molar ratio of hydrogen peroxide to sulfur (NO/NS), the molar ratio of formic acid to sulfur (NA/NS), an‎d the catalyst dosage. The optimum conditions were obtained at NO/NS= 16, NA/NS= 34, an‎d a catalyst amount of 0.6 g, under which a sulfur removal efficiency of 87.38% was predicted an‎d an experimental value of 86.92% was achieved. After five regeneration cycles by thermal treatment at 320 °C, the catalyst retained approximately 88% of its initial activity. Mechanistic analysis indicated that oxidation predominantly proceeded via controlled oxygen transfer from active molybdenum species. Overall, the HZSM-5-PMA system presents an efficient an‎d stable approach for the oxidative–extractive desulfurization of real fuels under mild conditions.

گوگردزدايي اكسيداسيوني , زئوليت ZSM-5 , فسفوموليبديك اسيد , گازوئيل , روش سطح پاسخ

Oxidative desulfurization , ZSM-5 zeolite , Phosphomolybdic acid , Diesel fuel , Response surface methodology

Mahyar Mansouri

Ahad Ghaemi