Oxidative Desulfurization Activity of NIT Nitroxide Radical Modified Metallophthalocyanine

In the present study, metallophthalocyanines were modified with NIT nitroxide radicals through chemical bonds to prepare a series of metallophthalocyanines–NIT catalysts (MPcTcCl(8)-NIT, M=Mn(2+), Fe(2+), Co(2+), Ni(2+), Cu(2+) and Zn(2+)) applied for oxidative desulfurization of thiophene (T) in model fuel. The MPcTcCl(8)-NIT catalysts were characterized by FTIR, UV-Vis, ESR, and XPS spectra. The oxidative desulfurization activity of MPcTcCl(8)-NIT catalysts was studied in a biomimetic catalytic system using molecular O(2) as the oxidant. The MPcTcCl(8)-NIT catalysts exhibited high catalytic activities for the oxidation of thiophene in model fuel. The desulfurization rate of ZnPcTcCl(8)-NIT for thiophene reached to 99.61%, which was 20.53% higher than that of pure ZnPcTcCl(8) (79.08%) under room temperature and natural light. The results demonstrated that MPcTcCl(8)-NIT catalysts could achieve more effective desulfurization rate under milder conditions than that of the metallophthalocyanines. The NIT nitroxide radicals also could improve the catalytic activity of metallophthalocyanine based on the synergistic oxidation effect. The stability experiments for ZnPcTcCl(8)-NIT showed that the catalyst still had a high desulfurization rate of 92.37% after five times recycling. All these findings indicate that the application of MPcTcCl(8)-NIT catalysts provides a potential new way for the desulfurization performance of thiophene in fuel.