Abstract
Catalytic oxidation is considered a viable method for reducing the sulphur level of transportation fuels and H2O2 is usually used as the oxidant. For this reason, it is essential that any extraction operation must remove the oxidation product from the fuel. A new oxidation method is studied in the present work. Instead of H2O2, air was used as the oxidant and phosphotungstic acid (PW) was used as the catalyst; the latter was imbedded in the pore spaces of the mesoporous silica material SBA-15 to form a PW/SBA-15 composite. The oxidation reaction occurred in the pore spaces of the composite and the polar reaction products were immediately adsorbed there. As a consequence, there was no need for a subsequent exaction operation. Desulphurization experiments were carried out using a model fuel composed of n-octane and thiophene. The content of thiophene was reduced from 2000 ppmw to less than 1 ppmw at 50°C and ambient pressure. The saturated PW/SBA-15 composite was regenerated at 350°C by using a nitrogen flow for 4 h. Such conditions allowed the catalytic activity to be recovered.