Ultra-Deep Desulfurization of Diesel: Oxidation with a Recoverable Catalyst Assembled in Emulsion

A [(C18H37)2N+(CH3)2]3[PW12O40] catalyst, assembled in an emulsion in diesel, can selectively oxidize the sulfur‐containing molecules present in diesel into their corresponding sulfones by using H2O2 as the oxidant under mild conditions. The sulfones can be readily separated from the diesel using an extractant, and the sulfur level of the desulfurized diesel can be lowered from about 500 ppm to 0.1 ppm without changing the properties of the diesel. The catalyst demonstrates high performance (≥96 % efficiency of H2O2, is easily recycled, and ∼100 % selectivity to sulfones). Metastable emulsion droplets (water in oil) act like a homogeneous catalyst and are formed when the catalyst (as the surfactant) and H2O2 (30 %) are mixed in the diesel. However, the catalyst can be separated from the diesel after demulsification. Cleaner fuel: The [(C18H37)2N+(CH3)2]3[PW12O40] catalyst, assembled in emulsion in diesel, can selectively oxidize 4,6‐dimethyldibenzothiophene‐like compounds to sulfones with stoichiometric amounts of H2O2 under mild conditions (see scheme). The sulfones can then be readily separated from the diesel by using extraction methods and the catalyst can be recycled. The sulfur level of the desulfurized diesel can be lowered from about 500 ppm to 0.1 ppm without changing the properties of the diesel.