Hierarchical-pore UiO-66 modified with Ag⁺ for π-complexation adsorption desulfurization

Adsorption desulfurization represents an alternative technology for the effective removal of thiophenic compounds from fuels. Metal-organic frameworks have been the ideal candidates for the adsorptive desulfurization of fuel due to the high surface areas. Pristine UiO-66 is thought to be appropriate for the removal of small thiophenic compounds. This work developed a new type of hierarchical-pore (micro and mesopores) UiO-66 with a higher specific surface area and porosity for the removal of larger adsorbates using MOF-5 as the template. To enhance adsorption desulfurization performance, the Ag⁺-exchanged hierarchical-pore UiO-66 (HP-UiO-66-SO₃Ag) with π-complexation was synthesized by the ion-exchange method. The HP-UiO-66-SO₃Ag samples were characterized by FTIR, XRD, SEM, TEM, and N₂ adsorption-desorption isotherms. Compared with the original UiO-66, the HP-UiO-66-SO₃Ag has a higher specific surface area, pore volume, and pore size. The static adsorption experiments showed that HP-UiO-66-SO₃Ag had a high adsorption capacity for thiophene and benzothiophene. Moreover, the HP-UiO-66-SO₃Ag sample still exhibits high adsorptive performance in the presence of toluene. The regeneration results show that about 90% of the initial adsorption capacity of HP-UiO-66-SO₃Ag can be regenerated after four cycles.