Deep oxidative desulfurization of gas oil by iron(III)-substituted polyoxometalate immobilized on nickel(II) oxide, ((n-C4H9)4N)4H[PW11FeO39]@NiO, as an efficient nanocatalyst
Mohammad Ali Rezvani, Kolsom Ghasemi, Hadi Hassani Ardeshiri, Masomeh Aghmasheh
Abstract
Abstract Sulfur compounds are among the most unfavorable constituents of petroleum derivatives, so stringent regulations have been established to curb their atmospheric emissions. In this regard, a new nanocomposite ((n-C 4 H 9 ) 4 N) 4 H[PW 11 FeO 39 ]@NiO) was synthesized composed of quaternary ammonium bromide salt of iron III -substituted Keggin-type polyoxometalate immobilized on nickel(II) oxide nanoceramics via sol–gel method. The assembled (n-C 4 H 9 ) 4 N) 4 H[PW 11 FeO 39 ]@NiO nanocomposite was identified by FT-IR, UV–Vis, XRD, SEM, EDX, and TGA-DTG methods. The characterization results exhibited that ((n-C 4 H 9 ) 4 N) 4 H[PW 11 FeO 39 ] dispersed uniformly over the surface of the NiO nanoceramics. The ((n-C 4 H 9 ) 4 N) 4 H[PW 11 FeO 39 ]@NiO nanocomposite was employed as a heterogeneous nanocatalyst in the extractive coupled oxidation desulfurization (ECOD) of real gas oil and dibenzothiophene (DBT) as a model compound. Under relatively moderate conditions, the catalytic performance of the ((n-C 4 H 9 ) 4 N) 4 H[PW 11 FeO 39 ]@NiO in the ECOD procedure was studied by incorporating acetic acid/hydrogen peroxide as an oxidant system at a volume ratio of 1:2. According to the ECOD results, the ((n-C 4 H 9 ) 4 N) 4 H[PW 11 FeO 39 ]@NiO demonstrated the effectiveness of up to 95% with 0.1 g at 60 °C under optimal operating conditions. Moreover, the ((n-C 4 H 9 ) 4 N) 4 H[PW 11 FeO 39 ]@NiO nanocatalyst could be separated and reused for five runs without a noticeable decrease in the ECOD process. This study provides a promising way to meet the target of ultra-low sulfur as an essential process in oil refineries.