Tuning electron configuration of metal sites for the diesel adsorptive desulfurization over ion-exchanged zeolite Y

Abstract

In diesel adsorption desulfurization, the coordination bonding between the adsorbent and sulfur compounds is interfered by aromatic compounds in diesel. Transition metal cation exchanged zeolites Y has exhibits exceptional anti-interference performance. In this work, the influence of electron configuration on coordination bonding is explored, specifically between the adsorbent and substrate, using both experimental and DFT theoretical methods. Initially, NiY, CuY and ZnY were synthesized and evaluated for their desulfurization performance in model solution (sulfur content: 25 ppmw dibenzothiophene [DBT]) with two toluene concentrations (1 w% and 3 w%). It is found that CuY showed the highest performance with retention rate at 70.2 %. Subsequently, DFT calculations revealed the binding energy between Cu(II) and DBT was −2.71 eV, higher than Ni(II) and Zn(II), and that between Cu(II) and toluene was −1.75 eV, lower than Ni(II) and Zn(II), indicating that the highest binding energy difference was responsible for the best adsorption capability. Apart from these, wave function analysis show the electron configuration between Cu(II) and DBT had the highest binding energy difference. Finally, the impact of electron configuration on adsorption performance is further investigated by modulating the electron configuration of Ni(II) to enhance/suppress its adsorption capability. According to the findings of this study, tuning the electron configuration is an effective strategy to develop materials in adsorptive desulfurization particularly for extra low sulfur content.