Enhanced performance of adsorptive removal of thiophenic compounds from model fuels and aromatics over Ag and Ce doped SiO2 aerogel composites

Abstract

Fabrication of adsorbent can play an important role in the adsorption desulfurization technology as a most promising deeply desulfurization technology. Ag2O/CeO2/SiO2 aerogel composites were synthesized, where the easy oxidation of Ce3+ into Ce4+ was realized by adding hydrogen peroxide, and were utilized to remove thiophenics from model fuels and aromatics. Compared with Ag2O/SiO2 and CeO2/SiO2, the adsorption uptake and solvent washing regeneration performance of Ag2O/CeO2/SiO2 for thiophene was obviously enhanced, and the adsorption selectivity for thiophene in the presence of aromatics was relatively close to CeO2/SiO2, attributed to that Ag2O/CeO2/SiO2 adsorbed thiophenics via the π-Ag+ complexation and S-Ce bonding, where the latter was main interaction. However, there was no synergistic interaction between Ag and Ce species acted as adsorption sites in the Ag2O/CeO2/SiO2, which could be supported by that the chemical state of Ag and Ce in Ag2O/CeO2/SiO2 was consistent with corresponding one in Ag2O/SiO2 and CeO2/SiO2, respectively. Among Ag2O/CeO2/SiO2 aerogel composites with different molar ratios of Si/Ce, Ag2O/CeO2/SiO2-50 performed the best, its adsorption uptake for thiophene, benzothiophene and dibenzothiophene from model fuels arrived at 20.4, 21.8 and 27.2 mg-S/gads, respectively. Langmuir and Freundlich adsorption isotherm models, the pseudo-second-order kinetic model could well describe the adsorption of thiophenics over Ag2O/CeO2/SiO2-50.