Mild Oxidation with H2O2 over Ti-Containing Molecular Sieves—A very Efficient Method for Removing Aromatic Sulfur Compounds from Fuels

This contribution relates a new application of Ti-containing molecular sieves as catalysts for the oxidation of aromatic sulfur compounds with hydrogen peroxide under mild conditions. The catalytic activity of TS-1 (titanium silicalite), Ti-beta, and Ti-HMS (hexagonal mesoporous silica) in the oxidation of thiophene derivatives with hydrogen peroxide was studied. While TS-1 demonstrated low activity due to restricted access of reactants into the porosity, Ti-beta and Ti-HMS proved effective under various reaction conditions, both in two-phase, solid–liquid, and in three-phase, solid–liquid–liquid, systems. The aim of the study was also to obtain information on the applicability of the oxidation method for the removal of organic sulfur compounds from fuels. Results show that the sulfoxidation reaction can be used for decreasing the sulfur content of kerosene without consumption of hydrogen and use of high pressure equipment. In this new method the polyaromatic sulfur compounds (benzo- and dibenzothiophene derivatives) are oxidized into their corresponding sulfoxides and sulfones which are then removed by simple liquid–liquid separation.