Brønsted acidic SILP-based catalysts with H3PMo12O40 or H3PW12O40 in the oxidative desulfurization of fuels

In this manuscript novel heterogeneous catalysts for fuel desulfurization via peroxide oxidation are reported. The obtained catalysts combine high catalytic activity and stability with perfect synthetic availability, their composition and structure were ascertained. The catalysts represent supported ionic liquid phases (SILPs): Brønsted acidic ILs, namely 4-(3′- ethylimidazolium)-butanesulfonate, with two heteropolyacids (HPA) (sulfated ionic liquid protonated by H3PMo12O40 or H3PW12O40). Silica and γ-Al2O3 were used as support materials. These compositions ensure higher stability of heteropolyanions and make the catalyst stable over several successive oxidation cycles. The most active catalyst based on phosphomolybdic acid provides a high conversion rate for thiophene, thioanisole, and dibenzothiophene (turn over frequency of about 150–1200 h−1 per mole of HPA). Another important benefit of the reported systems is the desulfurization of diesel fuel with a very high efficiency (residual amount of sulfur <10 ppm) under mild conditions.