Experimental and theoretical study of adsorptive interactions in diesel fuel desulfurization over Ag/MCM-41 adsorbent

• Published in: Adsorption : journal of the International Adsorption Society Vol. 26; no. 2; pp. 189 - 201
• Main Authors: Sales, Rafael Viana, Moura, Heloise Oliveira Medeiros de Araújo, Silva, Sergio Ruschi Bergamachi, de Souza, Miguel Angelo Fonseca, Campos, Leila Maria Aguilera, Rodríguez-Castellón, Enrique, de Carvalho, Luciene Santos
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.02.2020; Springer Nature B.V
• Subjects: Adsorbates; Adsorbents; Adsorption; Adsorptivity; Aromatic compounds; Chemisorption; Chemistry; Chemistry and Materials Science; Computer simulation; Desulfurizing; Diesel fuels; Dispersion; Emission analysis; Engineering Thermodynamics; Field emission microscopy; Heat and Mass Transfer; Industrial Chemistry/Chemical Engineering; Microscopy; Molecular dynamics; Morphology; Organic chemistry; Organosulfur compounds; Photoelectric emission; Scanning electron microscopy; Scanning transmission electron microscopy; Silicon dioxide; Sulfur compounds; Surfaces and Interfaces; Thin Films; X ray photoelectron spectroscopy; X ray powder diffraction; π-Complexation; Adsorptive desulfurization; MPI silica; DFT/ONIOM; Ag/MCM-41 adsorbent
• ISSN: 0929-5607; 1572-8757
• DOI: 10.1007/s10450-019-00088-4

Molecular dynamics simulation performed by the DFT/ONIOM method and X-ray photoemission spectroscopy (XPS) data were employed for studying the adsorbate-adsorbent interaction system in diesel desulfurization over Ag/MCM-41 produced from beach sand silica (MPI). The morphology and structure of the materials were characterized via powder X-ray diffraction (XRD), scanning transmission electron microscopy (STEM) and field emission scanning electron microscopy (FESEM) together with energy dispersive spectrometry (EDS) analysis. The results proved a high dispersion of different Ag nanodomains onto MCM-41 and their chemical interaction with support and sulfur compounds by π-complexation. The best fit of kinetic and equilibrium data to pseudo-second order (R 2  > 0.99) and Langmuir models (R 2  > 0.98), respectively, demonstrate the occurrence of chemisorptive/catalytic interactions with organosulfur compounds, as seen in the XPS results. Its adsorption capacity ( q m  = 31.25 mgS/g) was 10 times higher than that obtained for pure MCM-41 and double the q m for Ag/MCM-41(C) adsorbent from commercial silica. The computational modeling approach provided valuable insight towards molecular level understanding of the mechanism in aromatic S-compounds adsorption over functionalized MCM-41 and the role of Ag species in this process.