Manganese-Loaded Activated Carbon for the Removal of Organosulfur Compounds from High-Sulfur Diesel Fuels

The adsorptive capacity of activated carbon (AC) is significantly enhanced toward weakly interacting organosulfur compounds (OSC) from sulfur-rich diesel fuel. Sulfur compounds are selectively removed from diesel after surface modification by manganese dioxide (MnO2). A selective surface for OSC removal was created by loading MnO2 on the surface; pi-complexation between the partially filled d-orbitals of Mn4+ and the S atom is the controlling mechanism for OSC removal. Principal component analysis (PCA) of adsorption data indicated the significance of the Mn-AC mass and the temperature as experimental parameters according to the following correlation: OSC adsorption (mgSg(-1))= 3.94 (mass) -0.06 (part. diam.)-3.28 (temp)+ 0.02 (conc.). The kinetics of OSC adsorption confirmed that OSC removal by Mn-AC is a fast process in which 66% of the surface is filled in 30 min. Kinetic data were best fitted by pseudo-first-and second-order models compared to diffusion-based models. Surface and pore diffusion has only a minor role in the process.