Deep Oxidative Desulfurization of Fuels Using Peroxophosphomolybdate Catalysts in Ionic Liquids

Abstract

A combination of catalytic oxidation and extraction in ionic liquid (IL) was used for the removal of benzothiophene (BT), dibenzothiophene (DBT), and 4,6-dimethyldibenzothiophene (4,6-DMDBT) from the model oil. Three peroxophosphomolybdates+ and [C 16 H 33 NC 5 H 5 ] + ) were synthesized and characterized. In the catalytic oxidation desulfurization (CODS) system containing the peroxophosphomolybdate with short alkyl chain ([(C 4 H 9 ) 4 N] 3 {PO 4 [MoO(O 2 ) 2 ] 4 }) and H 2 O 2 , the process exhibited low sulfur removal (16.8%). However, with addition of 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim]BF 4 ), the extraction and catalytic oxidative desulfurization (ECODS) system remarkably increased the removal of sulfur to 97.3% (with stoichiometric amounts of H 2 O 2 ). The process was superior to the simple extraction with IL (16.3%). The results demonstrated that the ECODS system could deeply remove DBT from the model oil, and this desulfurization system could be recycled 4 times with slight decrease in activity. We also found that the catalysts with short alkyl chains exhibited higher catalytic activity than that with long alkyl chain in the ECODS system. Moreover, the reactivity of sulfur compounds decreased in the order of DBT > 4,6-DMDBT > BT.

Metal-Catalyzed Oxidation of C–X (X = S, O) in Ionic Liquids

“…When molybdic salts were used [21] the best catalytic system was obtained with the combination [bmim]BF 4 and Na 2 MoO 4 (Table 2) although very good DBT extraction (92.6-99.0%) was also possible to obtain with the other Mo-species catalysts tested. When other substrates were tested, the reactivity order in the EODS system was DBT > 4,6-DMDBT > BT, as reported in the previous work [20]. It was also possible to recycle the catalytic system five times, with a decrease in efficiency from 99% to 90%, which maybe due to the accumulation of the oxidized S-compounds retained in the IL phase.…”

“…On the other hand, stoichiometrically 2 mol of oxidant is consumed per mol of S-compound (when S-compounds are oxidized to sulfones), although 2:1 molar ratio O/S is not sufficient to achieve a good EODS efficiency. This result is justified by the self-destruction of the oxidant in the different reaction conditions, thus a molar ratio O/S higher than 2 is always required [20]. The H 2 O 2 selfdestruction is also a determinant effect in the reaction temperature selection.…”

Catalytic oxidation of thiophene and its derivatives via dual activation for ultra-deep desulfurization of fuels

“…More recently, a new and effective approach that is chemical oxidation in conjunction with ILs extraction (ECODS) has been explored in order to improve the efficiency of desulfurization [3]. However, to date, the efficiency of ECODS system for FCC gasoline is still low [4][5][6][7][8][9][10][11][12][13][14], because the major sulfur-containing compounds of FCC gasoline, thiophene, and its derivatives are difficult to be oxidized [15].…”

Desulphurization of Transportation Fuels by Per-Formic Acid Oxidant Using MoOx Loaded on ZSM-5 Catalyst

“…The FT-IR spectra of MoO x , WO x and VO x -ZSM-5 catalysts are shown in Figure 1, which was recorded in the wave length raging between 500 to 1350 cm −1 in order to locate the characteristic absorption bands for metal oxides. The FT-IR spectra of all the metal oxide supported ZSM-5 catalyst exhibit similar prominent absorption bands centred at wave lengths of 1150 -1170 cm −1 which can be attributed to asymmetric stretching of [26]. It can be concluded from these results that the impregnated metals oxides exist as polymeric oxides which are adsorbed the surface of ZSM-5.…”