The main focus of this paper was to explore the real diesel fuel desulfurization by various nanoporous carbons of different physicochemical properties as well as their chemically functionalized counterparts. The most important aspect is that this work combines both experimental tests with theoretical calculations, bringing new insights regarding real diesel fuel desulfurization. The publication resulted after a fruitful collaboration with the Maria Curie-Skłodowska University. We would also like to acknowledge the HELLENiQ ENERGY S.A. for the financial support of the PhD thesis of Eleni D. Salonikidou through ELKE AUTH.

Abstract

Experimental tests combined with theoretical calculations have yielded new insights into real diesel fuel desulfurization (rDeSulfur) using activated nanoporous carbons. The carbons were selected for their varying physicochemical properties and further were chemically treated to modify their surface chemistry, aiming to investigate the impact of the major physicochemical features on rDeSulfur. The experimental findings demonstrated that both porosity and surface chemistry play complex roles. Specifically, a high degree of graphitization and diverse pore size distributions enhanced adsorptive capabilities, with some carbon samples achieving ultra-deep desulfurization levels (<1 ppmwS). Theoretical calculations indicated that π-π stacking through dispersion forces was the primary mechanism of adsorption. While surface functionalities at the edges of graphene had minimal impact on interaction strength, structural defects, especially clusters of three quaternary nitrogen atoms or single defected vacancy with OH group, improved interaction energies, boosting adsorption effectiveness compared to pristine graphene. The study concludes that the effectiveness of carbons in diesel desulfurization depends heavily on graphitization levels, defects, and where specific functionalities are located. Lastly, although aromatic compounds in diesel, like benzene, toluene, and naphthalene, compete with thiophenics for adsorption, they have lower interaction energies, suggesting preferential adsorption of sulfur compounds over the aromatics.

Read full text here: https://doi.org/10.1016/j.cej.2024.157858