Vanadosilicate Molecular Sieve as a Catalyst for Oxidative Desulfurization of Light Oil

Abstract

An oxidative desulfurization process for light oil has been investigated using a vanadosilicate molecular sieve as the catalyst and H2O2 as the oxidizing agent. The catalytic activities for three kinds of vanadosilicates, having different structures and pore-size distributions, were compared with those for the corresponding titanosilicates. The oxidation of dibenzothiophene and benzothiophene in acetonitrile was catalyzed more effectively by vanadosilicates than titanosilicates, where the mesoporous vanadosilicate showed the highest activity. The vanadosilicate also accelerated the desulfurization of the actual light oil in an oil/acetonitrile two-phase system: the sulfur content of the oil was decreased successfully from 425 ppm to less than 50 ppm (ultradeep desulfurization level). During the process, nitrogen-containing compounds were also removed successfully from the light oil. However, the vanadosilicate, recovered following the reaction, could not be reused for further treatment of light oil. This is because the catalytic activity of the vanadosilicate decreases significantly during the reaction, owing to the dissolution of vanadium species in the silica framework into the acetonitrile solution.