Deep Oxidative Desulfurization of Dibenzothiophene in Simulated Oil and Real Diesel Using Heteropolyanion-Substituted Hydrotalcite-Like Compounds as Catalysts

Three heteropolyanion substituted hydrotalcite-like compounds (HPA-HTLcs) including Mg(9)Al(3)(OH)(24)[PW(12)O(40)](MgAl-PW(12)), Mg(9)Al(3)(OH)(24)[PMo(12)O(40)] (MgAl-PMo(12)) and Mg(12)Al(4)(OH)(32)[SiW(12)O(40)] (MgAl-SiW(12)), were synthesized, characterized and used as catalysts for the oxidative desulfurization of simulated oil (dibenzothiophene, DBT, in n-octane). MgAl-PMo(12) was identified as an effective catalyst for the oxidative removal of DBT under very mild conditions of atmospheric pressure and 60 °C in a biphasic system using hydrogen peroxide as oxidant and acetonitrile as extractant. The conversion of DBT was nearly 100%. As a result, because of the influence of the electron density and the space steric hindrance, the oxidation reactivity of the different sulfur compounds in simulated oil followed the order DBT > 4,6-dimethyldibenzothiophene (4,6-DMDBT) > benzothiophene (BT) > thiophene (TH). When the reaction is finished, the catalysts can be recovered from the acetonitrile phase by filtration. The recovered MgAl-PMo(12) retains nearly the same catalytic activity as the fresh material. Moreover, MgAl-PMo(12) was found to exhibit an ideal catalytic activity in the oxidative desulfurization of real diesel resulting in a total remaining sulfur content of 9.12 ppm(w).