Catalytic oxidative desulfurization technology of supported ceria based catalyst: physicochemical and mechanistic studies

Abstract

The catalytic oxidative desulfurization (Cat-ODS) process has emerged as a new technology to achieve ultra-low sulfur levels in diesel fuels. Various cerium based catalysts impregnated with Mn/Al2O3 were developed in this study. The catalytic activity of Mn/Ce/Al2O3 was higher than the monometallic catalysts, Ce/Al2O3. Under these optimum conditions: tert-butyl hydroperoxide (TBHP)/sulfur ratio of 3, 5.26%Mn/11.68%Ce/Al2O3, temperature of 45 °C, 30 min of reaction, complete removal of model organosulfur compounds were obtained. In addition, >90% of sulfur was removed in commercial diesel. High resolution transmission electron microscopy (HRTEM) analysis of 5.26%Mn/11.68%Ce/Al2O3 showed the presence of Al2O3, CeO2 and MnO2. The active sites responsible for the higher oxidative desulfurization activity were CeO2 and MnO2. The mechanistic study showed that the reaction between TBHP and DBT was efficient to produce corresponding sulfone, instead of sulfoxide compound using 5.26%Mn/11.68%Ce/Al2O3 catalyst.