Preparation Of Phosphotungstic Catalyst Series And Performance Of Oxidative Desulfurization For Diesel

The countries make stringent environmental regulations to limit the sulfur level in gasoline and diesel with the enhancement of environmental consciousness. Thiophene and thiophene derivatives are very difficult to remove by the hydrodesulfurization technique (HDS) due to their steric hindrance. Although HDS can achieve ultra-deep desulfurization of diesel, to achieve these conditions requires high temperature, high pressure and high hydrogen consumption. At present, oxidative desulfurization (ODS) becomes a hot research subject.In our experiments, ODS consists of two processes: the first step is the oxidation of sulfur compoundes assisted by ultrasonic wave, and the other step is the removal of oxidation compounds. In ODS, H2O2 was used as oxidant and different catalysts was used to test the effect of ODS. The catalysts which was used in ODS are H3PW12O40, [C16H33(CH3)3N]3PW12O40, [C16H33(CH3)3N]3PW12O40 supported on AlMCM-41 and [C16H33(CH3)3N]3｛PO4[WO(O2)4]4｝. The effects of catalyst and oxidant contents, reaction temperature and time were investigated in experiment.The results show that H3PW12O40, [C16H33(CH3)3N]3PW12O40, [C16H33(CH3)3N]3PW12O40 supported on AlMCM-41 exhibit good catalytic performance and sulfur removal efficiency were ca. 88%. [C16H33(CH3)3N]3｛PO4[WO(O2)4]4｝was the best catalyst in ODS. Under the conditions of 0.0489 g of polyoxometalate, H2O2/S=8, 60℃,10 min of reaction time, dealing with 4 mL of FCC diesel(1560ppm), the sulfur removal efficiency was 98% and it was still upto 84% after dealing with 24 mL of diesel.The catalysts were characterized by means of FT-IR. The results demonstrated that FT-IR spectra of fresh and regenerated catalysts were almost the same, and the catalysts have a relatively stable structure.