Evaluation of continuously mixed reactor configurations in the oxidative-adsorptive desulfurization of diesel fuel: Optimization and parametric studies

In this study, oxidative-adsorptive desulfurization technology was applied to raw diesel containing 1480.4 ppm sulfur. For oxidative desulfurization, the oxidant and catalyst were hydrogen peroxide and phosphotungstic acid, respectively. Two types of continuously mixed reactors: (1) continuous stirred tank reactor (CSTR) and (2) in-line mixer were evaluated under varying reaction temperature, mixing speed and diesel flow rate. For the in-line mixer system, the mixer speed and the flow rates for diesel and oxidant were modeled and optimized using Box-Behnken design of the response surface methodology. Optimization of process parameters resulted in sulfur removal of 85.90% at 18,000 rpm mixer speed, 500 mL min−1 diesel flow rate and 300 mL min−1 H2O2 flow rate. In the subsequent adsorptive desulfurization experiments, continuous fixed-bed adsorption using alumina removed 92.81% sulfur from treated diesel fuel thereby producing low-sulfur diesel that is within the allowable limit of Euro IV standard.