Deep oxidative desulfurization catalyzed by (NH4)5H6PV8Mo4O40 using molecular oxygen as an oxidant

- Organic sulfurs are oxidized to sulfone with 100% selectivity by POMs with O2.
- Aerobic oxidation of thiophene shows good efficiency with 97% conversion.
- Ultra-low sulfur gasoline and diesel are obtained almost no loss of their quality.
- High stability shows long duration.

(NH4)5H6PV8Mo4O40 (NPVMo) was evaluated in oxidation desulfurization of dibenzothiophene (DBT), benzothiophene (BT) and 4, 6-dimethyldibenzothiophene (4, 6-DMDBT) in a model oil using O2 as an oxidant. By controlling the reaction conditions, sulfur contents in the model oil were decreased from 500 ppm to < 1 ppm corresponding to DBT, BT and 4, 6-DMDBT with almost 100% yield of sulfone, respectively. Meanwhile, thiophene is one of the main sulfur species in gasoline, which is difficult to be oxidized in conventional oxidative processes and to be removed from fuels. Noteworthily, thiophene was oxidized efficiently at 97% conversion catalyzed by NPVMo and O2 as oxidant. Such high activity was attributed to the electron transfer between NPVMo and DBT. Meanwhile, NPVMo acted as a heterogeneous and stable catalyst and could be recycled ten times with a slight decrease in activity in the model oil. More importance was that NPVMo was also available for deep desulfurization for FCC gasoline and diesel to obtain almost clear products with extremely lower sulfur content (2.29 and 9.43 ppm, respectively) without formation of by-products of oxidation to loss their octane values.

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