Nitrogen Adsorption Compounds in the Presence of Dibenzothiophene on Mesoporous Materials for Obtaining Ultra-Low-Sulfur Diesel

This work presents the adsorption process of nitrogen compounds, namely quinoline (Q), pyridine (Pyr), and indole (In), from liquid fuels such as gasoline and diesel containing dibenzothiophene (DBT) as sulfur-containing molecules. These compounds were adsorbed on mesoporous materials, namely SBA-15 and SBA-16, in calcined form in batch mode using dodecane as a solvent represent to a diesel mixture. The main conclusion of this research is that SBA-15 showed a higher nitrogen adsorption capacity than SBA-16 for all molecules containing nitrogen and sulfur. A comparative study of nitrogen and sulfur adsorption confirms that selective removal of nitrogen compounds from fuels using SBA-15 was better than that of sulfur compounds. Moreover, an increase in the adsorption of Q was found with SBA-15 material compared to SBA-16. To explain this behavior, the solids were characterized using X-ray diffraction (XRD), nitrogen physisorption, and High-Resolution Transmission Electron Microscopy (HRTEM). A pseudo-second-order kinetic model, rather than a first-order one, fitted the nitrogen adsorption data best. Moreover, the Langmuir model was suitable for describing the adsorption of nitrogen compounds from simulated diesel fuel, instead of the Freundlich model, which means that nitrogen compounds are adsorbed in a monolayer.